I have a buddy who is what I would call a 'non-practicing muslim' and I trust him. Various catholics, protestants, even some jews but I figure they have some idea of 'karma' at least if not a bigger picture of judgment day. So I expect a certain amount of ethical behavior, even when 'no-one is looking' because God does see all.
Atheists, just animals looking for food until they die, I do not trust them. I know some atheists are nice, but so are some murderers and thieves. I do not trust them.