Born again christians, isn't all sin a matter of choice?

whether you want to claim having "a moment of weakness", the fact remains that you are still a sinner, and you've made the conscious choice to sin (seperate yourself from god), even after your rebirth. i understand nobody is perfect. but still, my question to you is this. why? why would you turn away from god after "witnessing his glory"? is the glory not that great that you would turn your back on it for a moment of weakness? wouldn't this contradict anything anyone has ever said about the greatness of god, if someone is so easily swayed away from him, even for a moment? it's like you're saying god is way better than everything on this planet, but because i'm weak i'm gonna cheat on my spouse, and thus turn myself away from god.