The noun 教友 (jiàoyǒu) means "church member," "fellow believer," or "parishioner." It refers to someone who belongs to a religious community, particularly a Christian one. For example, 成了教友 means "became church members."
他和几个教友一起组织了慈善活动。
Tā hé jǐ ge jiàoyǒu yìqǐ zǔzhī le císhàn huódòng.
He and several fellow church members organized a charity event together.
她的邻居也是教友,两家人关系很好。
Tā de línjū yě shì jiàoyǒu, liǎng jiā rén guānxì hěn hǎo.
Her neighbor is also a fellow church member, and the two families have a very good relationship.
很多教友每周都会聚在一起学习。
Hěn duō jiàoyǒu měi zhōu dōu huì jù zài yīqǐ xuéxí.
Many church members gather together every week to study.