And it was good

Matthew wanders into the room the other day with a pensive look on his face. 

"Mumma," he says to  me, "God made the Earth right?"
"Yup," I replied.
"He made the stars and the moon and all the planets?"
"Yes, he did!"
"He made all the people?"
"Yup."
"Then... Mumma? "
"Yes Matt?"
"...Who made God?"