Creator God: How about asking the child, who made his toy or toothpaste? (you may show him/her the company/owner name on the toys etc),Then slowly move on to moon, sun, stars, mountains? Every thing in the world has a creator behind it.
You may begin asking, son did you create the moon etc? Did his friend or his uncle created them? Let him say, No. And then you might point to the CREATOR (God), as told above by brother. R. Martin Snyder in Ps 19.