“Who made God? Where did God come from?”

Anything which has an origin (anything which came to be), is contingent.

That means it depends on something else for its existence.

God, however, is an eternal, necessary being.

He did not come to be (He has always existed).

He is not dependent on anything else for His existence (He is necessary).

God’s perfection means He is complete and does not depend on anything else.

Why do we need a necessary being?

Otherwise, we get no ultimate explanation of why any contingent beings exist: we are always passing the buck.

Some atheists suggest why couldn’t matter have always existed?

Material things are always contingent.

Even if we have an infinite chain of contingent things, we would never get an ultimate explanation of why the chain existed.

Besides, the 2nd law of thermodynamics (entropy) shows that the universe can’t have always been here. Otherwise we would have already reached heat death and would not have enough energy to discuss the question.

And there is a powerful argument due to David Hilbert that an infinite number of physical things cannot exist.  (The “Hilbert Hotel” leads to paradox: you could take an infinitely full hotel and put all the guests in the odd numbered rooms, leaving an infinite number of vacancies—crazy).