It is widely believed that God is a topic related to the subject religion. But some religions don't accept the existence of God, for example Buddhism, Carvakam, etc. Buddhism deals with this world and ethics of the person to have a comfortable evolved life of this world.
The religions which speak of God are also not of a single univocal opinion. Some say that He is all pervading i.e., He is everywhere and in all static and dynamic things, where as some say that He is ruling the whole universe sitting in a separate world other than this earth.