"Has anyone felt like leaving God altogether?"
That's a good example of a poor question, because people who actually believe in the Christian God usually don't think that they leave God. Those who stick with their God do so because, after coming to believe in him, either they love him or they're too afraid of his wrath to leave him.
On the other hand, people who no longer believe that such a Go exists cannot, by definition, think that they're "leaving God". You cannot leave something you don't think exists. For them your question is like asking, "Do you feel bad about leaving the Tooth Fairy?"
Some people who still believe in the Christian God do actually consciously leave him, but I think they do mainly for what many consider selfish reasons, such as to pursue fame, fortune, sex or whatever, despite still believing in this God. They don't really care about serious matters, and they expect to live short but interesting lives. Such people rarely are serious enough to post to a discussion board like this, and so you won't find them here to comment on your question.
AlanF