Exaggerated: Bob was a rapist and murderer (usually, but not always, in that order) of pregnant women, children, and puppies. Until he found God. He joined the Saintly Church as a priest, and devoted his life to serving God. Now, he's pure-hearted and kind, charitable to all who come before him, whether or not they are part of his flock.
Downplayed: Bob used to be a Jerkass, but then he started going to church and became a pretty nice person.
Justified: Alex was a priest himself and tried to show Bob the right way up until the very end.
Alternatively, Harsh and unforgiving Fundamentalist Knight Templar Bob becomes disillusioned with God and ultimately rejects religion. Without any cause for being a Knight Templar anymore, Bob becomes a nice guy and makes up for the wrong he did.
Subverted: It looks like Bob has reformed but it's actually part of a heist to steal valuables from the church.
Double Subverted: However, Bob's conversations with the elderly minister eventually make him confess and abandon his plan, turning to God instead.
Parodied: Bob converts, but the church he joins is pretty much just as bad as all the stuff he used to do, and Bob, having been converted to that, is an even worse person than before only now he believes he's justified.
Zig Zagged: Chaotic Evil Bob accidentally kills Alex, feels uneasy, and visits a church for the first time. There, he decides that it'd be a great idea to rob the place while he's here but a conversation with an elderly priest opens his eyes to the light of the Lord. He abandons his criminal tendencies and becomes an acolyte there. However, when street thugs desecrate the church, he shoots them all dead in rage, later judging himself unworthy of salvation and leaving it. He is soon found by Vatican's agents, though, who enlist him to kick ass for the Lord as part of a special unit. Still, his experiences in the unit are far from idealism, so he grows disillusioned with God and deserts...only to later to become Just Like Robin Hood complete with a friar sidekick.
Averted: Nothing changes Bob's Chaotic Evil alignment, even a confession.
Enforced: The show is being produced for, or perhaps by, a religious company, and is thus mandated by the producers to show a strongly positive opinion of religion.
Lampshaded: "God has helped so many before you to leave their lives of sin behind. Will you not at least give Him a chance?"
Invoked: Bob knows that the people trust the Church, so to prove his Heel-Face Turn to his former victims who doubt his change, he becomes a priest.
Defied: Bob is having too much fun being evil, so he refuses to enter any kind of religious building.
Discussed: "Bob, you've changed so much since you joined the Church. You used to be such a sinful, evil man, but it's like your life has done a 180!"
Conversed: "Betcha Bob's alignment is going to go from Chaotic Evil to Lawful Good now." "Why is that?" "He's just been initiated into the Church. That always changes them."
When some thugs insult God with blasphemy in The Church, Bob reaches out for his guns and shows the punks just what kind of Badass Preacher they are dealing with. After that, he judges himself unworthy of salvation and wanders off.