The Jewish people needed some laws and guidance. So someone created the Torah for them, and it gave them morals.
The Christians believed it wasn't good enough, so they created a new god to drop on top of the old, and changed the laws to their liking,
Islam took a different spin on it, And formed everything their own way.
Back then There was no Air conditioning, or drug laws, so some people went a little crazy, And claimed miracles.
This RoK article contains a nice summation of a few arguments for the existence of God. These were put forward by some of the greatest minds in history.
Just because modern society tends towards atheism, and atheists tend to shove their non-belief down everyones throats, it doesn't mean that theism is wrong or absurd.
Are you asking the differences between religions? If so, I will answer for you. I will explain some of the major religions for you.
Hinduism says that if you’ve been bad, you may come back as a rat or some other animal. If you’ve been good, you might come back as a prince. Buddhism denies that any God exists, and that life and death are sort of an illusion. Islam acknowledges the reality of sin and hell, and the justice of God, but the hope it offers is that sinners can escape God’s justice if they do religious works. God will see these, and because of them, hopefully He will mercy-but they won’t know for sure. Basically, if you did enough religious deeds and followed Islam the way you should, you get to Heaven. If you don’t do enough religious deeds and you don’t follow it as you should, you will not go to hell. If you don’t do religious deeds and do not follow it correctly, you will go to hell. Jews believe Jesus did not fulfill messianic prophecies that establish the criteria for the coming of the messiah. Christianity says that God is loving, but also equally wrath. He is a righteous judge and judges accordingly, and will one day judge everyone. God satisfied His wrath by becoming a human being and taking our punishment upon Himself. And when Christ rose, He paid our debt.
I would argue that you cannot make a logical step from the evidence presented to us as humans to the belief in any of these religions' doctrines and claims. Things like 'the design argument', which themselves can be argued against anyway, still do not offer any evidence for a god that actually favours particular people, cares how you act, what you eat, who you sleep with and how, what you wear etc. It is simply absurd.