In many religious philosophies God is creator of this universe, he is maintaining it and finally he will dissolve it. However, there are religions like Sanatan Dharm in which God has simply brought out this universe, and in the end the universe will be merged into Brahm, the Supreme God.
There are many names to represent the concept of God. Almost all the religions which believe in existence of God, has different names for him.
Most of the people today believe that God is one, but sages know him in various names.