Do heavily brainwashed Christians ever cast at least some doubt on the existence of their god?

By heavily brainwashed, I mean the Christians that actually read the bible back to front, still have no issue with the immoral concepts, and are thusly heavily brainwashed because they liked the idea of Christian schadenfreude too much. Do these poor souls have a chance at casting any doubt whatsoever and leaving their beliefs in the dust, or are their delusions set for life because their psychopathic characters happen to match the vibe from the bible and birds of a feather flock together?