Why would God use someone who doesn't believe in him?... apparently...?

Truthfully... many years ago I came across a homeless man on the street... for reasons I still can't explain, and never will be able to explain, I felt a compelling urge to help him out.... I brought him to my apartment and then got him welfare and a few weeks later was able to get him a job where I worked...(and the only thing I asked for in return was help with housework) now some 8 years later... he has his own place, is still working, and is married with a child (my god she's cute) and another on the way... The guy (Herb) says that it was God's will for me to find him and help... but I argue that point telling him I in no way shape or form believe in God, but he tells me that I must be joking as I even have Christ in my name (Christopher, funny coincidence I thought, my mother named me so because she thought I was a gift from God... yeah right, Satan's more like it...) and that God works in mysterious ways... but doesn't God (so to speak) turn away from those who have turned their backs on him as I have?. If so then God could not and would not have used me... what gives?... and will I ever do it again.. probably not... the first few days I was so afraid for my stuff, lol.