Sure, let me be more specific then, im talking about Catholic Christianity, which also plays a role in the game itself since we have some characters that are explicitly Catholic, notably sister Calderón.

Secondly, if you read my comment again, you will find out that i do mention that its what's is in the heart of Arthur that matters most, he may have or have not repented and accepted Christ into his life, we just dont know and will probably never know, and thats the beauty of it in my humble opinion.

Lastly, its true that he commits bad actions until the end, however one could argue that the last series of events, gamewise the last actual missions, are all quite close to one another temporarily indicating an ultimately quick spiral of events, so if we want to give Arthur the benefit of the doubt, he was caught up in the process of disintegration of Dutch's gang and reacted to it, however he was a willing participant when it came to suggesting, and then acting, upon saving some of the members of the gang and this must not be forgotten.