God is eternal. He never had a beginning and he will never have an ending. He has always been. He was not born. He was not created. He has always existed just as he is now. It is difficult for us with our finite human minds to comprehend this, but it is true.

Isaiah 57:15 For thus saith the high and lofty One that inhabiteth eternity, whose name is Holy; I dwell in the high and holy place, with him also that is of a contrite and humble spirit, to revive the spirit of the humble, and to revive the heart of the contrite ones.

Isaiah 44:6 Thus saith the LORD the King of Israel, and his redeemer the LORD of hosts; I am the first, and I am the last; and beside me there is no God.

Exodus 3:13 - 14

[13] And Moses said unto God, Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? what shall I say unto them?
[14] And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you.

Hebrews 13:8

Jesus Christ the same yesterday, and to day, and for ever.

John 8:51-59

[51] Verily, verily, I say unto you, If a man keep my saying, he shall never see death.
[52] Then said the Jews unto him, Now we know that thou hast a devil. Abraham is dead, and the prophets; and thou sayest, If a man keep my saying, he shall never taste of death.
[53] Art thou greater than our father Abraham, which is dead? and the prophets are dead: whom makest thou thyself?
[54] Jesus answered, If I honour myself, my honour is nothing: it is my Father that honoureth me; of whom ye say, that he is your God:
[55] Yet ye have not known him; but I know him: and if I should say, I know him not, I shall be a liar like unto you: but I know him, and keep his saying.
[56] Your father Abraham rejoiced to see my day: and he saw it, and was glad.
[57] Then said the Jews unto him, Thou art not yet fifty years old, and hast thou seen Abraham?
[58] Jesus said unto them, Verily,verily, I say unto you, Before Abraham was, I am.
[59] Then took they up stones to cast at him: but Jesus hid himself, and went out of the temple, going through the midst of them, and so passed by.