I'm going to do the best I can to answer, knowing that my answers may be insufficient. My belief in G-d is largely based upon sensing the divine, and I can't give that to you with an argument.
Who made god or why does he just exist?
Why is god the real god and not zeus/posidon etc?
I'm going to answer the second question first, because we will only have confusion if we don't have a clear idea what we mean when we say G-d.
The natural world is filled by a spendor that touches the human heart. I've stood beneath a Giant Sequoia and thought "I can understand why someone would say this is a god." I'm going to make a necessary sweeping generalization and say that the awe of nature was the beginning of spirituality. Eventually we had enough time for art, and began making symbols of these natural elements, idols reprenting rain, or fertility, or war. In some places this overlapped with reverence for ancestors, and the possibility of cheating death.
But as civilization grew, and the written word allowed us to stand on the shoulders of those who had come before, humanity began seeing a bit further than creation. We began to question the congruence of serving the god of love today, but the god of war tomorrow. All polythesitic cultures, if they exist long enough, eventually begin to speculate there is something behind all these masks of gods, a unified divine, whether it is all Brahma's dream, or the G-d of Abraham, Isaac, and Jacob.
A man asked the sage, " The Tao gives birth to 10,000 things, but what do the 10,000 things give birth to?" The sage replied, "I have a shirt I need to get washed." For those of you who have difficulty with deep metaphor, it means that the 10,000 things give birth to Tao, they return to the source.
There is a Zen story where the disciples asks the sage, "How do I achieve enlightenment? What is the secret." The sage says nothing, but simply holds up a single finger.
I've talked with phsycists who are really into chaos theory, and what strikes them as significant is that in the middle of all this chaos, there is pattern. The water of a rivers swirls this way and that, constantly changing, yet it always flows down. If there is design, does it not rather imply a designer?
Now there are differnt ideas about the Creator, or Tao, or the oneness underlying the universe. But I'm not going to waste time on the detail. If such an entity or essence exists, it is a marvel we can even perceive it, or hypothesize about it. We should not presume to think we can understand it. or him. or her.
THAT is the big step: everything after acknowledging the existence of G-d is really just so many words. The Tao which can be expressed is not the eternal Tao.
Now I can turn to your first question. Space-time is a construct of creation. If G-d is creator, outside of creation, then time and space mean nothing to him, nor do they bind him. We call this concept "Eternity." As He introduced Himself to Moshe, "I am that I am."
Why does it say in the bible that few people will go to heaven and most will go to hell? It doesnt make sense because god knows how our lives will turn out and what we will do before we actually do it. Why then, will he make most people go to hell? Isnt he a perfect and loving god?.
You are asking a question specific to christianity, so in all fairness, I will let the Christians reply. If you want the Jewish take on the afterlife, which is quite different, just ask. Otherwise I'll assume you don't want to be bothered. My PERSONAL take is simply that I leave the afterlife, IF there is one, to G-d; I just don't worry about it. My job is to live THIS day in THIS place in the way my creator calls me to, to be all that I can be and do all that I can do, with His help.
Humans only advantage is thier brain. We dont have claws etc and are fragile. I think if there is a god then he gave us a brain capable of figuring it all out. so that we choose to love him etc. If we cant figure it out then god is made up.
Ahhh but that IS the process. That as a species we are evolving the ability to sense and understand our own Maker. From the moment of the big bang, everything in this universe is set up to bring about the eventual evolution of sentient life. We are BECOMING. What we understand today is far more than we understood when we were pond scum. In the future, how much more will we understand than now?
Honestly, though, if you really really REALLY want to know if G-d exists, you need to put in the time and effort seeking him. Who knows what will click for you? Maybe you will find Him in the beauty of a Mass, in the depth of Buddhist meditation, the glory of a sunrise, the Torah of loving your neighbor as yourself, or even a child's laugh. He is everywhere, if you have the right eyes. When you find Him, it will be like Dorothy returning to Kansas, and realizing that what she went looking for had been there with her all along. Some journeys are longer and harder than others, so if you are serious about finding G-d, be ready to hurt and suffer on the quest. Seeking the Archenstone is a dangerous quest and quite frankly, you might not return. Some of us found G-d in the blackness of the pit, where we lay broken, when he came like a gentle lover and cried with us and nursed our wounds. There is a Zen saying "Don't mind the cracks, it's how the light gets in." Basically, (and don't let it get around that Jew quoted one of the gospels!) "Seek and ye shall find. Knock, and the door shall be opened to you."
May you be blessed in your journey.
