Probably due to his career slowing down. He's had a couple of huge songs in the past few years. Music industry doesn't care if you're religious unless it affects their bottom line. They'll squeeze every last dime out of anybody stupid enough to sign a contract

Being a musician isn't really worth it anymore unless you want to tour 24/7, and considering Bieber has had his fair share of controversies, he's probably happy to be a part timer