I've never intentionally converted anyone to being an atheist but I did unintentionally help convert the woman who later became my wife. We never talked much about it and I never said anything that really hit home with her all of a sudden. It was more the fact that she spent enough time with me to realize someone could be an atheist and be completely "ok" - I don't know if that possibility had even occurred to her before. Once it had, some nascent doubts sprang back up and she had no compelling reason to bat them down.

I wish I could be more specific but I really didn't pay attention to it. I care about people's (even my family's) religious beliefs or lack thereof about as much as I care about which sports franchises they are fans of - that is not at all.