How does God decide if you go to heaven or hell?

God doesn't decide whether we go to heaven or hell, we decide. Our actions decide. Everything in this world is controlled by the Law of Karma - as you sow so shall you reap, what you do will come back to you. Therefore, don’t imagine that God is sitting somewhere and directing the destiny of eight billion people. No! Don't imagine that somewhere, there is a a place called heaven and hell and you will take a flight or spacecraft and then you can go there. No, heaven and hell are experienced on earth, when we take rebirth. The body dies, after performing actions, but the one who has directed all the actions is ME, the Mind and the Ego. The mind and the ego is reborn based on Karma, our past actions and we come back to earth to experience heaven or hell based on our own actions. This is all controlled by God through the universal Law of Action and Reaction, the Law of Karma.