Back to the bible, you seem to have a lot of arguments that basically say "Everything bad about Christianity is the fault of people. But God and Jesus are a-ok!" But everything we know about God and Jesus has already gone through people with pens, so basically people has always corrupted the religion.
And read up on Mithraism.
Some more info i have gathered from a friend studying History at the University i'm at :
Noah :
"The story of Noah and his Ark is related to the Sumerian myth of a great flood. In the sumerian myth the man is named Ziusudra. Over time the myth spread westward until it ended up in the Jewish belief system. (A process known as Syncretism). "
The story of Exodus from egypt :
"No doubt that the writer of the story, or people who had an influence had been to egypt because many references were to real events in egypt. However, despite the huge calamities supposedly inflicted upon the Egyptians there is only one mention of Jews in all of the extensive writings of the Egyptians, and that is on a stone of Pharoh Sheshonk (the Biblical Shishak), simply mentioning a tribe called Israelites. Moreover, the story of a baby put in the nile and rescued, and then leading "his people" out of egypt was a popular myth around the Levant for over 500 years before the Jews started believing it. "
Satan :
"The concept of Satan and hell are Zoroastrian (a Persian religion) in origin. The Jews originally had no concept of hell, or as Satan the adversary. Zoroastrianism preached that all people's had free will. That everyone had a choice between the forces of good (those of Ahura Mazda) and of evil (Ahriman) and Ahriman was a devil character. In the end fable of Zoroastrianism the world faced an apocalypse where good defeated evil in a battle involving angels. The Jews who had been forcibly removed from the last two tribes in the kingdom of Judea by the invading Assyrians, and moved to Babylon (c. 600 B.C.) came into contact with these ideas. Afterwards, when they returned Satan went from being one of god's workers (see the Book of Job) to being an enemy working against god. And the idea of heaven and hell started to take root among some small groups of Jews. The most notable group of Jews who were influenced by this were the early Christian sects. Which then became a religion for everyone, not just Jews, hence the religious world we live in today."
God :
"Yahweh(later Jehovah, or just plain god), originally just called Yah (which is why you say Hallelujah, it means praise be unto yah), evolved out of the Canaanite pantheon. While the bible lists Baal as a false god in some of the later books, originally they were one and the same. Jews started out as a polytheistic cult. Originally, among the Jews, who were but one sect living in Canaan. The Jews, like the other Canaanites worshiped El the supreme god, and even more worshiped Baal(also called Bel). Over time the people came to believe in a number of manifestations of Baal called the Baalim, one of them called Yahweh. As happens in history over time one god takes precedent and Yahweh became a sort of chief deity.
As this evolved other gods were worship alongside Yahweh. Among caves in the dead see we have found pottery with figures of Yahweh (at that time depicted visually) and Ashtarte. Ashtarte was a godess at the time worshipped as Yahweh's consort. Archaeologists have found many shrines dedicated to her worship inside Jewish Shrines. Even the decalogue (ten commandments) does not deny other god's, it simply states the Yahweh is first "Thou shalt hold no god before me". Jews adhered to that believing that Yahweh was the chief god. By about 800 B.C. though, the trend towards monotheism had pushed farther, with the Prophets Hosea and others purging priests who worshiped other gods, thus completing a trend lasting some 1500 years."
Jesus :
"It is not like one day everyone was using the old Roman system and then everyone used A.D., it slowly came into formal use. B.C. as everyone knows means before Christ. A.D. however, does not mean after death like many people think. After all it would make no sense if it was before Christ one year, and after death the next, considering he lived into his 30's according to biblical passages. A.D. in fact, stands for Anno Domini, Latin meaning "The Year of Our Lord", denoting the Christian era. That being said, Christ was not born in the year 1 A.D. (There was no year zero). Due to descriptions of political circumstances given, Christ was almost certainly born in the year 4 B.C. the date of 1 A.D. was a miscalculation by Byzantine scholars in the 7th and 8th centuries A.D.
There are a number of problems however. For one the New Testament claims that the reason they returned to Bethlehem was because of the census, that all persons were required to return to the town of their birth. There is a little problem with this. First, there was no census in the year 4 B.C., nor one in the year 1 A.D. In fact the only census that it could have been was the census in 14 A.D. Moreover, no census in the Roman world, indeed any ancient census ever required people to return to the town of their birth, an impossibility in the ancient world, also one without little reason. The reason for this addition in the bible? It is quite simple. You often hear Jesus referred to as Jesus of Nazareth? Why? Because he was really born in the town of Nazareth. However, long before the birth of Jesus one of the prophecies of the messiah was that he would be born in Bethlehem, so the story of the census was added to place Joseph, Mary, and the baby Jesus at Bethlehem.
Another interesting note. Jesus was not called Jesus, or any version of the word. Jesus was in fact called Joshua, or rather the Aramaic version of that name, the everyday speech of the people in the region. Jesus would have been called Yehshuah. The name Jesus Christ is another Greek origin, since the New Testament was originally written in ancient Greek, then used along with Latin by the many learned people through the empire. Jesus comes from the Greek Iasu (Greeks had no letter J, the letter I was used instead) meaning healer, and Christos meant the anointed one, a phrase used commonly for priests and other important people. Therefore Jesus Christ was not so much a name as a title."
And finally!
Homosexuality :
"Certain persons of a right wing persuasion use the book of Leviticus to say that god is against homosexuality "Thou shalt not lie in bed with mankind like thou liest in bed with womankind..." However, up until this time, and indeed even after homosexuality was not just a tolerated, it was a social norm. The Jews shared a common thing that much of the ancient world had, including the Greeks and the Romans, one could indulge in homosexuality if you will, without being considered homosexual, and still have wives and such on the side. It was not just something a few people did, but most men. Morever, prostitution was not only indulged in, it was sacred. Like many near eastern religions, the Jews had not only secular prostitutes, but also temple prostitutes. The ancients thought that the orgasmic feelings of sex brought one closer to the gods (or god). The Jews not only had temple prostitutes, they had homosexual temple prostitutes. However, around the time of Leviticus it became necessary to raise the birth rate, so homosexuality became a very undesirable thing, hence it became "bad" in the eyes of god. However, temple prostitution and temple homosexuality were still considered legit even after Leviticus because it was in the temple, it was only after a process of fading out after a few hundred years did it disappear altogether"