Someone has said that everything that once was not, but now is, must have had a beginning. Another way of saying that is, everything that has begun must have had a beginning. This might seem like too obvious a statement, but it wasn't that long ago that it was assumed by some learned people that all matter had simply always existed.
Prior to the middle or so of the twentieth century, it was believed by some scientists that the universe had always existed. This idea of the universe being eternal gave some comfort to those sola-naturalists looking for an explanation for the origin of time, space, matter that didn't involve God. But as a theory championing omni-naturalism as the explanation for everything's existence, it was doomed in the mounting barrage of evidence that now points to the universe having a beginning. This new understanding of the origins of the universe was coined "The Big Bang Theory."
The "Big Bang" theory proposed that the universe must have had a beginning since its current expansion can be traced back in time and space to a single event. Einstein's theory of relativity (E=mc2) also supports this theory. In essence, Einstein has observed that the universe is relative to its beginning. Within this relativity are certain fixed laws, like the speed of light.
So we now know that the universe did have a beginning- about 14 billion years ago - and that it has certain fixed laws, such as the speed of light and gravity, and that it is still expanding from its original starting point in the cosmos.
Curiously, these concepts have been declared by the Bible for thousands of years. "In the beginning God created...", "God has fixed the laws that govern the universe...", "He stretched out the heavens..."
When we ponder these thoughts we realise that the only One who had no beginning was God. He is eternal. This satisfies the question: If God made everything, who made God? Only those things which had a beginning must have had a beginner. God has always been. He therefore had no beginning. Curiously, it's often the hyper-naturalists who reject and dismiss this concept of God as the Eternal who just a generation earlier were espousing that everything was eternal.