But your whole premise resides in your belief that God exists.
Let me ask some questions.
Why did God not present himself to any of the ancient cultures? Surely they were his children even as you yourself is.
Why would God promise the Jews so many things in the old testament, yet turn on them and make christians the chosen ones?
Why would so many cultures in the modern world not believe in the God of the bible if he were indeed omnipotent? Again, are not all people his children?