教会(jiào huì) - church (as an organisation or congregation) in Mandarin

教会 (jiào huì) is the church as a body of people: the congregation, the denomination, the institution that owns property and runs schools. It is the word you want for the Catholic church, the local congregation, or church history.

The pairing to learn is 教会 against 教堂. 教堂 is the building with the roof and the pews, so you walk into a 教堂 and you belong to a 教会. English lets one word do both jobs, which is exactly why learners reach for the wrong one: 我去教堂 means you are going to the building, 我去教会 means you are going to the gathering.

There is a second trap hiding in the same two characters. Read with a first tone, 教会 (jiāo huì) is a verb phrase meaning to teach someone until they have got it: 他教会我开车 is he taught me to drive. Same characters, different word, and only the tone on 教 tells them apart.