What reason does God have for punishing people on Earth?
The “problem of evil” that you are addressing has been a sore point for all theists for thousands of years. The obvious answer, that some Christians accept, is that God does not cause these things to happen, but he allows these things to happen. In the end, as the Christians say, it is just a matter of faith. One of my colleagues, whose parents were liberal Buddhists, explained that he “accepted” the fact that his parents would burn in Hell. Further, he explained that if all his children, of which he has four, all died in some horrible way, it would not shake his faith in God. Clearly, there is no relationship between what happens in this world and God belief. Those who see a kind, loving force operating in the world are wearing blinders.