Translation guide
In Japanese, 'Baptist' is typically expressed using the loanword バプテスト (Baputesuto) or the term バプテスト派 (Baputesuto-ha). When referring to a person, バプテスト教徒 (Baputesuto kyōto) or simply バプテスト can be used. The concept is directly borrowed from English, so the katakana form is standard.
Referring to the Baptist church as a Christian denomination
The most common and direct way to refer to the Baptist denomination in Japanese. It is a loanword from English and widely understood in Christian contexts.
彼はバプテストの教会に通っています。
He attends a Baptist church.
Literally 'Baptist sect/denomination'. Used when explicitly distinguishing the Baptist denomination from other Christian groups.
バプテスト派は成人洗礼を重視します。
The Baptist denomination emphasizes adult baptism.
A less common, more literal translation meaning 'immersion baptism church'. Rarely used in modern contexts; mostly found in historical or academic texts.
浸礼教会は17世紀に始まりました。
The Baptist church began in the 17th century.
Referring to a person who is a member of a Baptist church
Can be used to refer to a Baptist person, though context is needed to distinguish from the denomination. Often used with 教徒 (kyōto) for clarity.
彼女はバプテストです。
She is a Baptist.
Explicitly means 'Baptist believer/adherent'. Clearer than just バプテスト when referring to a person.
私の友達はバプテスト教徒です。
My friend is a Baptist.
In most everyday situations, バプテスト is sufficient and natural. Adding 派 or 教徒 is only necessary when you need to be precise or avoid ambiguity.
あの人はバプテストですか？
Is that person a Baptist?