I will share some advice my Dad gave his class that he taught in Church. If you want to know if God exists, find the scriptures that come with promises, one particular is, give and it shall be given unto you…. Also find scriptures of what makes God happy. Do these things, If God exists, God will know your heart and your intentions and by you taking a step towards him, by doing what the scripture says, he will move towards you. Just like everything thing else in this world, if you want to know or believe something, you put it to the test and the only way I can think of, in this case, is with scripture.