Sri Chinmoy: When a child asks you, "Who is God?" just ask the child to look into a mirror and to smile as soulfully as possible. The word 'soulfully' the child may not understand, but the child can easily see how beautiful he looks. Tell the child to try to give the most beautiful, absolutely the most beautiful smile, and to look at himself. The child will know whether it is a beautiful smile or just an ordinary smile. So, the more beautiful the smile the child gives, the more divinity comes forward. When the child looks at his own face, at his most beautiful, glowing consciousness, you tell him that that is God and nobody else.
Who is God? God is our own highest reality. If you can give a most soulful smile that will immediately illumine you and the whole world, that smile is nothing other than God. Let the child remain in the consciousness of his most beautiful smile, a smile that pervades the length and breadth of the world. The child's most beautiful smile is the most convincing answer. In the case of adults, they have to pray and meditate and develop a divine consciousness. But for a child, this is the easiest and most effective answer. And at the same time, it is absolutely true. You are in no way fooling the child.