"taken faith in Christianity" does not sound right. The closest thing that you may be thinking of is "taken up the Christian faith". If he was previously a follower of another religion then "converted to Christianity" is probably the most usual phrase.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
tamguatlayThanks, GPY.I have read that one embraces a religion. I wonder whether there are other words.You can "adopt" a religion too.