Esperanto and the Religions: An Unexpected History

Esperanto has no religion, says so out loud, and has said so since 1905. The Declaration of Boulogne defines Esperantismo as nothing but the effort to spread a neutral language, and then adds, in its own last sentence, that any other idea an Esperantist attaches to it is lia afero pure privata. The interna ideo article tells that story, and tells you what it cost Zamenhof to hold the line.

And yet no other constructed language, and few natural ones, has attracted anything like this list. A Catholic union recognised in canon law by the Vatican. A Protestant league older than the First World War. A Buddhist league founded in 1925 by an Englishman and a Latvian. A Quaker society, a Jewish association, a Bahá'í league, an Islamic association, an Orthodox circle, and, because the universe has a sense of humour, a worldwide atheist Esperanto organisation founded in 1987.

This page is the honest version of that story. Several of the things Esperantists most like to say about it are wrong, and the wrong ones are flagged as they come.

Zamenhof's own starting point

Zamenhof was a Jew from Białystok in the Russian Empire, and the religious question was never abstract for him. He wrote his first universalist doctrine in 1901 as hilelismo, addressed to Jewish readers and named after Hillel, and rewrote it in 1906 as homaranismo, deliberately stripped of its Jewish framing so it could be offered to everybody. The interna ideo article owns that chronology in full and this one will not repeat it.

What matters here is the hinge. Homaranismo was a religious-ethical programme with a language attached, and the movement made him choose. At Boulogne in 1905 the interfaith stanza of his Preĝo sub la verda standardo was kept out of the recitation; at Kraków in 1912 he renounced any official role. The history article tells that part.

So the pattern was set before any of the confessional associations existed. Esperanto the movement would be neutral. Esperanto the language would keep being picked up by people whose faith made them universalists, precisely because it was neutral, and none of them would be speaking for it.

The Catholics got there first

The chronology here is routinely told backwards, so take it slowly.

In 1902 a French priest, Emile Peltier of Tours, founded a society called Espero Katolika together with Henri Auroux and with his bishop's permission. The society could not be formally registered, so the founders started a newspaper of the same name instead, and its first issue appeared in October 1903. Peltier died in 1909, aged thirty-nine.

The union came afterwards. Internacia Katolika Unuiĝo Esperantista, IKUE, was founded in 1910, at the first Catholic Esperanto congress in Paris, the year after its founder's death. So the magazine is seven years older than the organisation it now belongs to, and the man who started both did not live to see the second.

The oldest-magazine claim needs an asterisk. IKUE's own site says flatly that Espero Katolika estas la plej malnova daŭre aperanta E-revuo, the oldest continuously appearing Esperanto magazine. The Esperanto Vikipedio puts the same claim in the past tense, oni nomis ĝin dum longa tempo, it was called that for a long time, and the reason is that the continuity is broken. It stopped for both world wars, and it stopped again in 2022 and 2023: four issues dated 2023 were printed together in March 2024, and the first 2024 issue appeared that June. The honest sentence is that it was founded in 1903 and has been published, with interruptions, ever since. UEA's own directory still lists it in 2026 as a quarterly, with IKUE at roughly 700 members.

What the Vatican has actually done

More than the sceptics expect and less than the movement claims. Four dated facts, all of them formal acts:

The 1990 approval is the strongest of them, because it is a decision of a Vatican department about liturgy rather than a friendly word at a congress. The printed Missal and lectionary for Sundays and feasts followed in 1995, two volumes with a Vatican imprimatur, and were reissued on CD-ROM in 2002 jointly by IKUE and the Protestant league. The 1992 decree recognised IKUE as an international association of the faithful of pontifical right, which is a real canonical category and not a courtesy.

Vatican Radio's Esperanto service began in January 1977, on a proposal Giacinto Jacobitti had put to the pope in 1964; he edited it until 1980. It went from once a week to twice in 1980 and to three times in 1998, which is where the listening guide picks it up as one of the four scripted broadcasters still producing. The programme paused in July 2023 when its long-serving editor stepped down and resumed that August under a new team led by Marija Belošević, who is also IKUE's president.

Two things everybody repeats that are not true

No pope has ever celebrated Mass in Esperanto. Cardinals and archbishops have, repeatedly, at IKUE congresses. The nearest a pope has come is that Cardinal Karol Wojtyła planned to celebrate one at the 37th IKUE congress in Częstochowa in 1977 - which was, incidentally, the largest IKUE congress ever held, with more than seven hundred participants. He was not yet pope. As pope he spoke Esperanto to IKUE gatherings in 1991 and 1997, which is a different and smaller thing.

The pope no longer greets the world in Esperanto, and has not since 2013. This one is worth spelling out because it is quoted everywhere in the present tense.

John Paul II added Esperanto to the multilingual Urbi et Orbi greeting at Easter 1994 and used it at Easter and Christmas until his death in 2005. Benedict XVI continued it throughout his reign; at Easter 2008 the greeting ran to sixty-three languages. The wording was fixed: Feliĉan Paskon en Kristo resurektinta at Easter, Dibenitan Kristnaskon kaj prosperan novjaron at Christmas.

Then Francis dropped the multilingual greetings altogether at his first Easter, in 2013, and never brought them back. Leo XIV has revived the practice since 2025, but at ten languages, not sixty-three: the Christmas 2025 and Easter 2026 texts on the Vatican's own website run Italian, French, English, German, Spanish, Portuguese, Polish, Arabic, Chinese and Latin. Esperanto is in neither. I checked both documents rather than taking anybody's word for it.

The Protestants, and the magazine that predates them

Kristana Esperantista Ligo Internacia, KELI, was founded on 25 August 1911 in Antwerp, during that year's World Esperanto Congress. Its membership is described in its own encyclopedia entry as Lutherans, Calvinists, Methodists and Baptists, sed ankaŭ kelkaj katolikoj kaj ortodoksuloj, plus some Catholics and Orthodox. So: Protestant-led, with an open door, rather than ecumenical as a matter of constitution.

Exactly the same trap as with the Catholics: the magazine came first. Dia Regno was founded by a German engineer, Paul Hübner, and first appeared in February 1908, three years before the league existed. It runs six issues a year and is still going; KELI is listed as active in UEA's 2026 directory, with its 74th congress scheduled for Görlitz in 2026.

The joint venture is the one place this section has to use the past tense. The Ekumena Esperanto-Kongreso was a shared IKUE and KELI congress, first held at Limburg in 1968 in the thaw after the Second Vatican Council. There were twenty-two of them. The last was at Poděbrady in 2018, and the Vikipedio entry records flatly that en la jaroj 2019 ĝis 2024 ne okazis Ekumena Esperanto-Kongreso. Both bodies now prefer their own. If you read that Catholic and Protestant Esperantists hold joint congresses, that was true for fifty years and has not been true for eight.

The Bible

The complete Protestant Bible in Esperanto is the Londona Biblio of 1926. Zamenhof translated the Old Testament from the Hebrew and finished in March 1915; the New Testament was done by a committee of English and Scottish clergy, completed in 1910 and published in 1912. The reading list treats it as a translation monument and that is the right shelf for it.

The books missing from a Protestant canon were supplied later, and by a surprising hand: Gerrit Berveling, a Dutch classicist and a pastor in the liberal Remonstrant church, who published the deuterocanonical books in two volumes in 2001 and a third in 2008, alongside his own translations of the Gospels (1992) and Paul's letters (2004). He is often described as having produced a Catholic Esperanto Bible. He did not; he is a Protestant, and the Catholic liturgical texts are the separate 1990 and 1995 story above.

Oomoto: the strangest chapter, and the best documented

Now the part nobody expects.

Oomoto is a Japanese new religion, founded in 1892 by Deguchi Nao, a poor peasant woman in Ayabe near Kyoto, on the strength of a possession experience. Her son-in-law Onisaburo Deguchi, who married her daughter Sumiko in 1900 and took the family name, turned it into a doctrine and a movement. He was a universalist of an extravagant kind, and his slogan survives carved on a monument raised in 1963:

Unu Dio, Unu Mondo, Unu Interlingvo.

One God, one world, one international language.

That was coined in Esperanto, not translated into it.

The date is June 1923, and the movement's own history page gives the detail: an Esperanta Stud-Societo founded on 28 June 1923, renamed the Esperanto-Propaganda Asocio that October, and later the Esperanto-Populariga Asocio, EPA, which still exists in Kyoto. Oomoto sent representatives to Japan's first Esperanto congress at Okayama on 31 August of the same year. The 1924 date you will sometimes see is not the adoption; it is when Oomoto began publishing in Esperanto, and its Esperanto organ first appeared on 31 January 1925.

The quotation everybody gets wrong

Onisaburo Deguchi is routinely quoted as having called Esperanto the language of the spirit world. I went looking for that and could not find it in any source, primary or secondary, and neither could a full-text search of either Wikipedia. It is almost certainly a collapse of the title of his principal scripture, Reikai Monogatari, which Oomoto itself renders in Esperanto as Rakontoj el la Spirita Mondo, Tales of the Spirit World. Dropped.

What he did say is on Oomoto's own website, in a set of verses with a prose commentary dated 1 July 1923, and it is better than the myth:

Ĝuste Esperant' kun forta influpovo de la vortanim' ja iĝas granda helpo por la nobla misiad'.

Esperanto, precisely, with the strong influence of the word-spirit, becomes a great help to the noble mission.

Dank' al Difavor', la disvastiĝ' de l' sankta instruaro de l' homamo, realiĝas per la lingvo Esperant'.

Thanks to divine favour, the spread of the holy teaching of love for humanity is realised through the language Esperanto.

Mi do elkore deziras ke ĉiu sufiĉe studu ĉi tiun lingvon.

So I sincerely wish that everyone would study this language sufficiently.

The load-bearing word is vortanimo, literally word-soul, which is the Esperanto rendering of the Shinto concept kotodama, the spiritual power residing in words. That is a far more specific and far more interesting claim than the myth: Onisaburo was not saying Esperanto is spoken by spirits. He was saying that Esperanto carries the word-spirit, and is therefore fit to carry a mission. Note also the apostrophes, Esperant' and vortanim', which are the Rule 16 elisions doing their metrical work in what are, after all, tanka.

Note the honesty caveat: these are Esperanto renderings published by Oomoto of its own founder. They are excellent evidence of what Oomoto teaches, and weaker evidence of Onisaburo's exact Japanese wording, which I could not retrieve.

Zamenhof in a chapel

The claim you will read is that Oomoto worships Zamenhof as a god. What Oomoto's own question-and-answer page says is more careful than that, and it qualifies the word itself:

La kvalifiko de la vorto dio, donita al la spirito de Zamenhof, ne havas la saman signifon kun ordinaraj prapatraj spiritoj.

The qualification of the word "god", given to Zamenhof's spirit, does not have the same meaning as with ordinary ancestral spirits.

Oomoto vidas, ke la spirito de Zamenhof eĉ nun daŭre agadas kiel misiisto de la anĝela regno; do, lia spirito estis apoteozita en la kapeleto Senrej-ŝa (sanktejo, kie estas apoteozitaj la spiritoj de jam mortintaj Oomoto-misiistoj), kaj oni sincere kultas lian spiriton kune kun aliaj misiistoj.

Oomoto sees Zamenhof's spirit as still active now as a missionary of the angelic realm; so his spirit was enshrined in the little chapel Senrej-sha (a shrine where the spirits of deceased Oomoto missionaries are enshrined), and his spirit is sincerely venerated together with the other missionaries.

So: enshrined in the chapel for departed missionaries and venerated alongside them, which is a real and specific religious act, and not the same as elevation to the rank of a major kami. The flat English summary is fair but lossy, and the Esperanto original is right there to check.

And then the state came

Oomoto's Esperanto work was stopped by the same reflex that closed the German and Soviet associations. The Second Oomoto Incident began on 8 December 1935; the headquarters and shrines were physically destroyed, Onisaburo was imprisoned for about six and a half years, and Oomoto's own history page records the consequence in four words: Interrompiĝis Esperanta movado de Oomoto. The movement was refounded on 7 February 1946 and the Esperanto work resumed with it.

It is the same shape as the Nazi and Soviet episodes in the history, and it is one of the reasons this article exists. A state that wants one people, one language and one loyalty has an identical problem with a universalist religion and with a neutral language, and when a movement is both it gets hit twice.

Today EPA still runs, publishes the trilingual monthly Nova Vojo, and is credited with around a thousand active Esperanto speakers among Oomoto's membership; the Kameoka facilities carry Esperanto signage. The missionary arm, Universala Homama Asocio, takes its name in conscious allusion to Zamenhof's homaranismo. One honest limit: the Esperanto magazine Oomoto has a public archive that stops at issue 460 in 2013, so I am not claiming it is currently published.

The Bahá'ís: encouraged, useful, not chosen

This is the case where the movement's telling is most often too strong, and where the primary sources are easiest to check, because they are all online in English.

Bahá'í scripture calls for a world language and never names Esperanto. Bahá'u'lláh's Lawḥ-i-Maqṣúd asks that

"the divers languages be reduced to one language and in like manner the scripts used in the world be confined to a single script... It is incumbent upon all nations to appoint some men of understanding and erudition to convene a gathering and through joint consultation choose one language from among the varied existing languages, or create a new one, to be taught to the children in all the schools of the world."

That is a procedure, not a product: governments consult, and then they choose. Esperanto is one of the things they might choose.

'Abdu'l-Bahá then encouraged it warmly and repeatedly. Addressing the Paris Esperanto Society on 12 February 1913: "Now praise be to God that Dr. Zamenhof has invented the Esperanto language. It has all the potential qualities of becoming the international means of communication." And earlier, in 1912: "All through America I have encouraged the Bahá'ís to study Esperanto."

And then his successor drew the line, in writing. Shoghi Effendi's ruling on the subject is the single most useful paragraph in this whole article, because it settles a question Esperantists keep reopening:

"Regarding the subject of Esperanto; it should be made clear to the believers that while the teaching of that language has been repeatedly encouraged by 'Abdu'l-Bahá, there is no reference either from Him or from Bahá'u'lláh that can make us believe that it will necessarily develop into the international auxiliary language of the future... Pending this final choice, the Bahá'ís are advised to study Esperanto only in consideration of the fact that the learning of this language can considerably facilitate intercommunication between individuals, groups and Assemblies throughout the Bahá'í world."

Encouraged, useful, explicitly not chosen. Any page telling you the Bahá'í faith has adopted Esperanto is overreading its own scripture.

The Bahaa Esperanto-Ligo was founded on 19 March 1973, after nine Bahá'í Esperantists consulted at the 1972 World Esperanto Congress in Portland, Oregon, and the Universal House of Justice approved it by letter on that date. Its bulletin is BELmonda Letero. It is still going.

Lidia

The human link is the one that hurts. Lidia Zamenhof, the author's youngest daughter, encountered the Bahá'í faith at the 17th World Esperanto Congress in Geneva around 1925, introduced there, on the fullest account, by Martha Root - an American Bahá'í who had begun learning Esperanto in 1912 and used it across a 1923 to 1924 tour of Japan, China, Australia and New Zealand. The same circle is what eo.Vikipedio credits with bringing Esperanto to Onisaburo Deguchi's attention, which quietly ties this section to the last one.

Lidia became a Bahá'í and spent much of her working life as an Esperanto teacher and translator, putting Esslemont's Bahá'u'lláh kaj la Nova Epoko, Bahá'u'lláh's Libro de Certeco and 'Abdu'l-Bahá's Parizaj Paroladoj into the language. She went to the United States in late 1937 at the American Bahá'ís' invitation. The Immigration Service refused to extend her visitor's visa on the ground that teaching Esperanto for money was illegal paid labour; she declined the marriage offers that would have let her stay, and sailed for Poland in December 1938.

She was murdered at Treblinka in the autumn of 1942. No exact date is known, and I am not going to invent one.

The smaller shelves

The Esperanto Vikipedio's list of specialist associations has a religion section with eighteen entries. It attests that they were founded; it does not attest that they still function, and several plainly do not. Taking the better-documented ones:

• Budhana Ligo Esperantista, founded 1925 by A. C. March of London and Edgar Grot of Riga; a Japanese branch founded in 1931 by the Zen monk Shibayama Zenkei; refounded in 1948 by Rudolf Petri and again at the 2002 congress in Fortaleza, and active since. Its magazines were La Budhismo from 1931, Darmo after 1948 and La Lumo Orienta in Japan. The Dhammapada exists in Esperanto twice over, as Petri's La vojo al Nirvano aŭ la Dhammapado (1973) and Gunnar Gällmo's La Darmo-pado. Worth noting for the vocabulary: ReVo's headword is budao with buddo and budho as equal spellings, and budaismo beside budhismo, so the league's budhana is entirely regular even though this site's word list leads with the buda- forms.
• Kvakera Esperanto-Societo, founded 1921 with Ralph Eliott as its first president, and the only one of the small bodies whose entry says in the present tense that it still runs, nuntempe oni organizas precipe en kaj per la interreto.
• Hebrea Esperanto-Asocio, founded 1925 to bring together Jewish Esperantists across states, with Izrael Lejzerowicz as its first president. Lejzerowicz was murdered in the Holocaust and I can find nothing to suggest the association survived him.
• An Islama Esperanto-Asocio founded in 2007, and a Universala Islama Esperanto-Asocio that the encyclopedia describes as historical. Neither has an article of its own and I can find no evidence of current activity. Named here for completeness, not recommended as a link.
• Ateista Tutmonda Esperanto-Organizo, ATEO, founded 1987, which belongs on this page precisely because it proves the point about neutrality from the other end.

The vocabulary that comes with the subject

You cannot read any of the above without the words for it, and this chapter is where most of them arrive. Esperanto's religious vocabulary is the international stock taken at face value, so if you know the English you know almost all of it.

Three of them repay a second look. Pastro and pastoro are a genuine minimal pair and not a spelling slip: a pastro is a priest, a pastoro a Protestant minister, and the extra o is the whole difference. Meso is specifically the Catholic Mass, while diservo is the general word for public worship and is built the transparent way from dio plus servo. And the -ism- suffix does what it always does: kristanismo, budaismo and islamo are the doctrines, while kristano, budaano and islamano are the people who hold them. The one to watch is islamo, which is already the doctrine without a suffix, because the root arrived from Arabic with that meaning attached.

So why does this keep happening?

Two reasons, and they are the same reason.

The first is doctrinal. Universalist faiths have a language problem built into their premises: if the message is for everybody, the medium should not privilege anybody. Bahá'u'lláh wrote that down in the nineteenth century. Onisaburo Deguchi put it on a monument. The Second Vatican Council's opening to other Christians produced an ecumenical Esperanto congress within three years. A neutral language is not a curiosity to a movement of that shape; it is an obvious tool.

The second is that this is exactly what frightened the states. The persecution chapters of the language's history are not about grammar. They are about a movement whose loyalties crossed borders, and the German, Soviet and Japanese authorities each reached the same conclusion about it independently. Oomoto was hit in 1935 for being a universalist religion with an international language; the German association was dissolved in 1936; the Soviet union's members were arrested until it stopped functioning. The property that made Esperanto attractive to the faiths is precisely the property that made it intolerable to the regimes.

And then the deflation, which this page owes you. The associations are small. Espero Katolika stopped for two years and restarted late. The ecumenical congress has not met since 2018. The Bahá'í institution has said in writing that Esperanto is not the chosen language. The pope has not said Feliĉan Paskon since 2013. Whatever this is, it is not a groundswell.

But it is real, it is documented, and it is odd enough to be worth knowing. A Warsaw eye doctor built a language on the belief that the diversity of tongues is the chief cause of human enmity, insisted for the rest of his life that the language itself must stay neutral, and then watched half a dozen religions adopt it anyway, for his reasons, without his permission and without any of them being able to claim it.

He would probably have found that the correct outcome.