Who is God ?

Who is God? Ram,Shiv,Ganesh,Allah,Ishu,Sai,Durga,Gurunanak
Some times I think who is our God
Is Our God is Ram

if our God is Ram then who is Shiv,Ganesh ,Allah,Ishu,Sai,Durga,Gurunanak etc.
If all are our God then Why Sai Baba said "Sabka Malik Ek"
If God is one Then why God created so many names.
Some one tells that God resides inside us if resides inside us then whats name of that God.
Lot of Question to know definition of God.

Answer :
But finally I got answer that if there is no structure or name then remembering
or praying him is very difficult that's God created so many name.

You can select to pray as you like.

I suggest everyone pray to God but keep in mind that God is one so you can love to all cast person.
Actually love is great , God is great.