First, this objection makes a categorical mistake. It would be like asking, "How does your favorite song smell?" It just does not make sense, does it? This objection is often asked by those who are fans of the famed atheist, Bertrand Russell who once said, "It everything must have a cause then God must have a cause." But everything does not need to have a cause.
And it is here that God is lifted high and lofty in a category all His own, which takes us to our second understanding.
Second, there are several kinds of being. There is self-caused where something has caused itself to exist. This is implies several things that do no apply here. There are contingent causes. These are things (including people) who are caused by another. And there is this type of causation we know as "uncaused" where the God of the Bible is found.
God is the uncaused Cause. He is the beginning-less Beginner. He is the uncreated Creator. God is the Cause (the first Cause) of all that exists. Think of it this way. Every painting has a Painter. Every product has a Producer. If there is an origin, then there must be an Originator. And since there is a beginning (a genesis) there is a first Generator. That generator is God.
Exclaimed right from the very first verse of the Bible the Scriptures announce, "In the beginning God created the heavens and the earth" (Genesis 1:1). God is far from being created. God is the Creator of all things. He is the Cause of all first causes.
Think back to what God said to Moses at the burning bush as He was appointing him to confront the Pharaoh of Egypt.
"Moses said to God, 'If I come to the people of Israel and say to them, 'The God of your fathers has sent me to you,' and they ask me, "What is his name?" what shall I say to them?" God said to Moses, "I AM WHO I AM." And He said, "Say to the people of Israel, 'I AM has sent me to you'" (Exodus 3:13-14).
As the One who was not made, God was saying, "Moses, go tell them that the One who never began to exist (unmade) sent you.
God is unlike us. We are contingent beings where God is a necessary Being. We are dependent beings where God is an independent Being. The universe is contingent. God spoke the universe into existence. This means that all things that have begun to exist are dependent on God for their existence.
Third and finally there is a problem with the question, "Who made God? The word made cannot be said of God. For God is the unmade Maker.
If you look all around us, look at your desk, your car or your computer. Somebody made that. Everything that exists around us had a cause for its existence. Wouldn't it be easier to say that Somebody made that? Or how about this. Wouldn't be easier to believe that Something or Someone took nothing (Genesis 1:1) and made something than to believe that nothing took nothing and made something?
So the next time someone asks you, if God created then universe then who made God, take these three thoughts with you and share them with your friend asking this objection. It might get them to investigate the Christian faith a little deeper. It also may cause you to look into more learning how to answer more objections to your faith.