Just a preface. I don't believe in God. Any god. But I'm from a small (see tiny) rural eastern Canadian town. A village, really. Needless to say, a lot of people there believe in God (the Christian God). That being said, I was never forced to do anything I didn't want to do. I was never mistreated at the hands of religion. My dad's side of the family is from the United Church. My mom's side of the family is from the Salvation Army. My paternal grandparents were involved in the church. My grandmother played the organ and my grandfather was the sexton. Though he had said some things from time to time that indicated that he wasn't necessarily a devout worshiper. But being in a small town, church was just something you did. You didn't question it. Later on, my mom became the organist, which she does to this day. Yet I get the feeling that my parents aren't exactly the most religious either.

I went to Sunday school (United Church) every Sunday. Of my own free will. But I didn't really believe in the whole thing even then. I just enjoyed going to Sunday school as well as a Salvation Army-based youth group. I liked hanging out with my friends and this was a convenient way to do so. I would never disrespect religion or the religious organizations that I attended. I just started thinking logically at a fairly early age and realized that it was something I didn't believe in. And sitting in Church was something I didn't like wasting my time with, if I didn't have to. I don't hate God. You have to believe in him to actually have feelings towards him one way or the other. But getting older, it's obvious that some things done in the name of religion are pretty horrific. Just as some things done in the name of religion are beneficial to the world.

Anyways, now that you know where I come from, how would I react to discovering that God was real, without a doubt?

Assuming this is the God from the bible, then I guess I'd be forced to worship him, wouldn't I? Because otherwise I'd be fucked and spend eternity in Hell. But love him? Absolutely not. The God of the bible, putting it lightly, is a bit of a dick. Drowning the vast majority of humanity and land-based animals. "Testing" people by forcing them through the worst imaginable situations. Demanding that we worship him lest we spend eternity in hell. He's an asshole. But I'd play the game. I'd worship him. I'd do what it took to end up in the less shitty version of the after life. But I suppose that if this is the god from the bible, then he would know that I wasn't sincere in my love and I'd be fucked either way.

So, to recap: Worship? Yes. Love? No.

The evidence of God´s existence is anyone´s personal faith. That´s all that is to it.

Oh its not just these 2. There are other incidents. My family land is between 2 graveyards, one dating back to the 1800s. People who have been there see things they shouldn't have.

Don't take this as an attack or casting doubt on your knowledge, but i have to ask, have you actually read the Bible? 

You are free to interpret the bible text as you wish, but everyone knows that most is not factual and there are lots of tales because the text was written to try to teach lessons into His people and most of the people would only understand it if metaphors and personification were used.

Can you tell me where did you read the claim you do on your 3rd phrase? 

What if he did a mistake and wanted to destroy mankind, he's own creation? Does that make him bad? Was he bad or was the creation bad? He after that found some good in us and gave us another chance, seeing today's humanity, he was right both times, we are capable of many bad and atrocious things and also capable of good and and wonderful. You have the ability to focus on the humans that were destroyed and blame the evil God or to focus on the suffering of the God that had to resort to the last thing and have to come to the decision of destroying his own creation, because it was a bunch of no good doers. The text can be interpreted both ways,  some interpret in a way and some in another, that says more about the reader than about the writer or the tale written there.

First off, I would like to thank the OP for his own honesty about his likely reaction to (hypothetical) 100% proof that his belief in God is wrong.  Of all the atheist answers so far, I think "go into denial" hasn't been one of them—explicitly, anyway!  Maybe a few are masking it. 

I think I will have to give more than one answer to your own question. 

1.  First I will assume you mean "the God of the Bible".  But even this is an interesting case because it seems to me that the way he acts has changed significantly from OT times to NT times to today.  Does he act in different ways to us based on our cultural development to try to spur us on in different ways?  If we advance further from where we are today will he act differently towards us in yet a new way?  What is really happening to those who die?  (Different Christians believe different things:  Purgatory for example.)  If the Bible is completely true then I would have to take another look at it to see if a God that did those things, and then changed how they act towards us, was one I should revere.  Having some insight into their motivations would help. 

To me the Book of Job, in particular, is really inexcusable.  I can't see how anything could justify such a petty act.  I have a post on this subject here.  Now, of course this could be countered with "all part of the Plan" but I don't know how I could just blindly assume that was true.  Despite all that, though, it might be forgivable depending on all the rest of it—but to be clear, if I didn't have specific knowledge of an excellent reason to let this happen it would be me forgiving God for his past misdeeds. 

Faced with the prospect of Hell, I think I would go with "Twilight Zone" style false worship if that would be enough to qualify me for Heaven.  Like JWeinCom, I am not so proud that I would refuse to bow to save my life.  However, if I would have to do horrible things in his name in order to get the reward it would be a different story. 

2.  If the question is limited to exactly what you said, "a supreme, eternal, almighty being had created you and the Universe, and was the very thing that sustained everything," then I would certainly be grateful for my existence, but how grateful I was would depend on what "sustain everything" means. 
2a.  If God is simply "keeping the lights on" and doesn't have any specific control over events, then the bad things that happen aren't God's fault and we should be grateful for what we are given even if it's an imperfect gift.  (However, I'm not sure if my feelings would rise to "love and worship" or just be deep admiration and gratitude.  A favor we could probably never repay, but not one that really influences day to day life or that I think about on a daily basis.  Send them Christmas cards and so on.  If we are asked to do something, do it.) 
2b.  But if God has absolute control over the universe (with the exception of our own free will) and still throws hurricanes and asteroids and smallpox at us, well—why should I love such an abusive parent?  Sure, we wouldn't exist without them, but that doesn't mean it's okay to smack us around.  I'd recognize what God did for us but still resent them. 

People claim to see all kinds of things that have absolutely no basis in fact. In fact studies have shown that people can firmly believe they have seen things that never existed when studied in a controlled setting.

If it was all true what Catholicism said, and therefore God being real, then without a doubt yes. Hell sounds like an awful place!

It is said in Genesis. The christian god regretted making humans.

God acts and has feelings as things unfold forward. A god that knows everything, that knows how humans will act in front of of the Forbidden Fruit even before he makes Adam, is not a god that should be shaken, sorry, disappointed, at the outcome. The god in the bible is a god that reacts to events as they unfold, instead of a god that knows everything from the start and that should say instead when confronted with Adam and Eve eating the forbidden fruit: "things are going according to plan."

A god that is everywhere and knows everything does not leave Adam and Eve with the forbidden fruit and then returns to see what happened and feel sorry about it.

The reason why this god feels regret by thinking he made a mistake and the reason why this same god is allegedly everywhere and knows it all is simply that he is described by different writers with a different idea of how he should be.

2) but everyone knows that most is not factual and there are lots of tales because the text was written to try to teach lessons into His people and most of the people would only understand it if metaphors and personification were used.

Yeah, some things are fiction and some things are factual, what and who determines what is factual and what is fiction? For a christian is simple, discard as fiction that which makes no sense or presents contradiction. It is impossible to have a reasonable argument with a person that discards as fiction, as a little story to teach something, those things that exposes the contradictions of the bible and how god is depicted.

OK, I will say that among those things that were exagerrated and that are fiction in the Bible we have Jesus being the son of god and that he performed miracles. You don't agree? Jesus being the son of god part is factual? How can you prove that among the things that aren't factual in the bible Jesus story isn't in among them, beyond your wish of it to be true?

3) What if he did a mistake and wanted to destroy mankind, he's own creation? Does that make him bad? Was he bad or was the creation bad? He after that found some good in us and gave us another chance, seeing today's humanity, he was right both times, we are capable of many bad and atrocious things and also capable of good and and wonderful. You have the ability to focus on the humans that were destroyed and blame the evil God or to focus on the suffering of the God that had to resort to the last thing and have to come to the decision of destroying his own creation, because it was a bunch of no good doers. The text can be interpreted both ways,  some interpret in a way and some in another, that says more about the reader than about the writer or the tale written there.

a) I have rough days where I may wish to punch everyone that even dares to cross eyes with me, but the problem is that your god is portrayed as someone perfect that knows it all, someone that laid down a plan for everything which cannot perturbed by any single thing, laid down since the beginning of everything, and that he is supposed to be perfect.

b) God cannot find in us "some good" and give us a second chance, there isn't a single thing that god can find in us because he created us, he knows what is inside of us, and he is supposed to know everything about us even before he created us, remember that god is supposed to know everything. right?

God knows everything, god created us knowing everything we have and don't have, he is supposed to know everything we will ever do, god knew what would happen with the forbidden fruit and yet he gave us that test, a test he knew we would fail and cursed us and blamed us for it.

There would have to be questions. Wich relegion is the right one? Why does it defend A or B when its imoral to do so. Why do you do nothing about the suffering in the world? About the killings done supposidly in your name by religion A or B? Why did you allow the "wrong" religions to exist when they are a trap when you are born in them and then torture us in hell for it? Why do you give us a brain with wich to understand the world around us through and ask us to believe you without any evidence?
Quite honestly, if he was the beeing described in several religions i would be quite wary. Even if he wasn't and was this loving and caring persona that allows the wrongdoings and doesn't intervene cause he can save everyone in the end, its a pretty sadistic game to play.

But you know... it makes no logic for a God to even exist. He is not necessary for a universe to exist and there is no evidence of his existance. It's just wishful thinking, just like every other fantasy in my opinion. So, it doesn't really matter. If he did exist we would all be his slaves and what we think would be irrelevant. I do guess Christopher was right in wich that would probably be a worse fate.

You can say whatever you like. I already said I'm  not here to sway opinions.