The God of the Bible is eternal.  In fact, His name, Yahweh (I AM), reflects this truth.  One of the questions asked by skeptics is "who created God".  The answer is simply "no one".  No one made God, that is why He is God, because He depends on nobody.  He is altogether sufficient in Himself.  In contrast, everything that is created, has a dependency on other things for sustenance and survival.  A plant cannot grow without soil, sun, and water.  Humans and animals cannot live without food and water.  Yahweh needs none of these elements. 

"I am the Alpha and the Omega," says the Lord God, "who is, and who was, and who is to come, the Almighty" (Revelation 1:8).  The whole of Scripture attests to the eternal nature of God.  So, I have selected this verse because it really captures the essential picture of this truth of the eternal God.  He is, He was, and will be.  He is God, has always been God, and will always be God.  He is the beginning, the first, and He is the end, the last.  Think on it, before there was a universe, before He spoke it into existence, He was.  And when this universe dissolves to give way the the new creation, He will be.