The chance that some sort of divine entity created everything (as in, made the Big Bang happen, thereby setting everything in motion) is pretty slim. Not impossible, but slim.
The chance that the god you are subscribed to is the right god, is even fucking slimmer.
The chance that that god, actually agrees with your specific beliefs about slavery, adultery, homosexuality, and cares about each one the the same extent as you do, and demands the same punishment for sins as you do, and rewards the same good deeds as you believe to be valuable, is almost fucking impossible. Is fucking impossible.
Perhaps a better way to approach the situation of life would be to try to be a good person, based around morals you think are reasonable, not based around beliefs claiming to be fact. Just try to be a good person for yourself, for society.
If there is no god, you've done alright, and death is the end.
If there is a god, but heaven and hell are bullshit, you've still done alright, and death is still the end.
If there is a god, and he's not as retarded as religious texts make him out to be, and he likes your morals and the way you lived your life, he'll probably let you into heaven.
If there is a god and heaven is reserved for people with vastly different morals, then that's not a place I want to spend my eternity, and maybe I'll enjoy the company in hell a lot better anyway.