Dear Friend:
You have asked a question that I'm sure millions have asked. The answer will probably not satisfy you but here's my attempt at it.
I have put that answer further down because I want to add my two cents and figured you would not get to mine thoughts if they followed the "technical answer".
Humans think in terms of what we see and experience. We think in terms of "cause" and "effect" because everything we see and experience stems from that. A "cause" is something that happens that causes something else to happen OR has an "effect". We have never see or experience anything else, so humans have trouble understanding the existence of God because when we think of God, we think there had to be a "CAUSE" for God, or something BEFORE GOD.
BUT
GOD IS THE "EFFECT" WITHOUT ANY "CAUSE". Because if God was the result of a cause, then there must be something before God, there would have to be a "cause" to create God. Then we would have to continue to cycle back and back, inifinitely.
Have I lost you completely by now...lol.
What I do know is that what I see and experience is NOT INIFINITE but had a beginning. There are two competing explanations for the origin of the universe. EVOLUTION or GOD CREATED.
I accept by FAITH that GOD CREATED everything or the universe some time in the past because I believe that there had to be a EFFECT WITHOUT A CAUSE. That doesn't mean I fully understand it, "God himself stated, that His Ways and Thoughts were far beyond Human understanding." My paraphase of Isaiah 55:8-10. I have no trouble believing that. And this is precisely why I can not believe in the Evolutionary explanation for everything I see.
Evolution can not explain the EFFECT without a CAUSE. No matter how much time Evolution says it took, they can not explain how it started if there was no STARTER.
Evolution basically says: "NOTHING" plus "NOBODY" times "VAST AMOUNTS OF TIME" = EVERYTHING. No matter what they say, it comes down to HOW DID IT START?, WHERE DID IT COME FROM? WHAT'S KEEPING IT GOING? HOW DID THE INCREDIBLE COMPLEXITY OCCUR? HOW WILL IT END? Evolution has no answers to these questions.
So friend, I beleive GOD did not originate but has always existed. God was the STARTER of everything. God is beyond human comprehension. Yet God loves you and is reaching out to you to believe in HIM and accept HIS free gift of eternal life through Jesus Christ His Son. GOD says, from the moment of your conception you became an eternal being also, but you will exist forever either WITH GOD(Heaven) or separated from GOD(Hell).
I took this "technical" explanation from another website.
Where did God come from?
"We can only partially comprehend the notion of God's existence. To do so, we must use human concepts to speak of God: "without beginning or end"; "eternal"; "infinite", etc. The Bible says that He has always existed: " . . . even from everlasting to everlasting, thou art God" (Psalm 90:2). And, "Your throne is established from of old; Thou art from everlasting" (Psalm 93:2). Quite simply, God has no beginning and no end. So, where did God come from? He didn't. He always was.
To us, the notion of time is linear. One second follows the next, one minute is after another. We get older, not younger and we cannot repeat the minutes that have passed us by. We have all seen the time lines on charts: early time is on the left and later time is on the right. We see nations, people's lives, and plans mapped out on straight lines from left to right. We see a beginning and an end. But God is "beyond the chart." He has no beginning or end. He simply has always been.
Also, physics has shown that time is a property that is the result of the existence of matter. Time exists when matter exists. Time has even been called the fourth dimension. But God is not matter. In fact, God created matter. He created the universe. So, time began when God created the universe. Before that, God was simply existing and time had no meaning (except conceptually), no relation to Him. Therefore, to ask where God came from is to ask a question that cannot really be applied to God in the first place. Because time has no meaning with God in relation to who He is, eternity is also not something that can be absolutely related to God. God is even beyond eternity.
Eternity is a term that we finite creatures use to express the concept of something that has no end -- and/or no beginning. Since God has no beginning or end, He has no beginning. This is because He is outside of time."