As you say: If God exist?
Many people are under the question to consider if God exist?
There do also exist many different kinds of Religions!
But when you come to the question why God is playing all high and all mighty, then i can might help answering that!
God and Satan are the two opposite sites or as you might can call them, Leaders, of the Religion; Christianity!
Satan has the ability to corrupt the human mind with both all kind of different diseases, but he can also plant different kinds of feelings within us, like greed, sorrow, fear, lust or rage.
While Satan has the abilities to interfear with the human mind, body and feelings, then God in fact dont have that much power! (Or at least thats what i heard, but then still God created all univers, so God got to have some powers!).
When God created all univers, planets and the people, then Satan came like a bully and destroyed his creations! And man came to earth and ruled. Then God came to the beliefs that he should help man and he put Jesus on earth to guide and help man, but Satan once again interfeared with his plans and made man doubt on Jesus intentions and then in the end killed him, and there are millions of other stories like this!
So over time God has tried to help man with living! Hoped that helped you a little in your far greater question!
God made man!
But maybe man made God!
We do shape the earth!
Just keep believing!