What is Eternity and Who Created God?

If God created everything, who created God?

God was not created, formed, or even born. The easiest way to say it is that God has always been. This is a difficult concept for many people, including Christians. It invariably leads to another question; What did God do before creating the universe? The question results from a misunderstanding of the word eternity. Eternity doesn't mean forever in the future. Eternity means without time. There was no 'before God created the universe,' because time did not start until the creation. "In the Beginning..." was the beginning of time as well as space and matter.

Perhaps an easier way to explain is like this.

Imagine a line representing time. Most people would see the line extending forever in both directions. Somewhere on the line would be the creation of the universe (either by God or the Big Bang.) Somewhere else would be the end of the universe (if you believe there will be one.)

Your life would also be on the line beginning at some point and moving right toward some other point. Humans can only move from left to right on the line. That is we can only go forward in time.

Most people who believe in God would say that God also exists on the line but He is able to move both forward and backwards on the line. That is God can move both forward and back in time and concern himself anywhere in history

To better understand the relationship between God and time, though. It helps to think of the line this way.
Imagine a line that begins at a definite point and ends at a definite point.

The starting point would be Genesis 1:1; the creation of the universe. The ending point would be Revelation 20:11; the end of the universe. Humans still exist on the line moving from left to right, forward in time.

But where is God? God does not move along the line, God exists outside the line; able to see the entire line at once

This also explains God's omniscience (all-knowingness.) God knows the future because he sees the future at the same time he sees the present and the past. Not only that, but remember God created the line. Which means he alone knows how long it will be. Eternity is the area outside the line. It is not just forever into the future but means without time at all. Why will there be no sun or moon on the new earth? (Revelation 21:23) Not just because God will be the light. The other purpose of the sun and moon is to mark time. (Genesis 1:14) There won't be a need for the sun or moon because there will be no time to measure.

This, of course, is not a perfect explanation, but I hope it helps.