i was wondering whether the gospel accounts of Jesus can be called evidence for Christianity being true, as they are all hearsay without any other eye-witness or contemporary accounts..
Also, a common reason christians will use to claim that christianity is true, is that "If Christianity was a lie, how come it has been accepted and spread by so many people throughout such a long period of time"
i was wondering how other atheists apart from myself would answer such questions??
You are correct about the Gospels being hearsay. There are no contemporary, extra-Biblical accounts that verify the historicity of Jesus. At best, you could say that the Gospels are evidence that at least some people believed that Jesus was a real person. And there could have been a real person at the heart of these stories - we just don't have enough evidence to conclude that that is true.
The number of people who believe a claim is not evidence for the truth of that claim. Furthermore, the people who make that claim will back away from it the minute you point out that most people on the planet today as well as throughout history have disagreed with them. If lot's of people think Christianity is true, then there are lots more who think it isn't - and, of course, they all worship The One True God (TM).
To answer your question about evidence, there is actually no available evidence to prove objectively that any religion is true, but there are outstanding witnesses to the events in Judaea in the first half of the first century AD. One is Philo of Alexandria who says nothing about Jesus, Christianity or any of the events described in the New Testament. Though there are some later references outside of biblical to Jesus, the lack of first-hand evidence alone makes them hearsay. Hearsay is not considered reliable evidence. There are no eyewitnesses who are named or who wrote anything, all the writings are by people that never knew Jesus and wrote after his supposed death. This would never fly with anything being written about actual history. None of the contemporary historians (people who lived at the time) wrote one word about a miracle working Jesus. The Jesus Christ of Christianity is unknown to historians living in the same place and time period that Jesus was supposed to have lived.
It is well known that the time period in which Jesus is said to have lived was a time when many men were named Jesus and many political leaders assumed the title of Christ. In ancient countries, divine Saviors were born of virgins, preached a new religion, performed miracles, were crucified as atonement for the sins of mankind, and rose from the grave and ascended into heaven. Jesus Christ of Christianity is unknown to history but all that Jesus was supposed to have taught was in the literature of the time; there is not one new idea.
Most scholars do not believe that there is any reliable evidence that a miracle working god-man Jesus lived. There is no evidence that supports a historical Jesus. There are no manuscripts written by Jesus or any artifacts. All claims about Jesus come from writings of other people. There is no contemporary Roman record that shows Pontius Pilate executing a man named Jesus. Jesus was supposed to have lived at a time when some of the greatest scholars, historians and philosophers lived in Greece and Rome. And some of the greatest Jewish writers lived in Palestine, but nothing was written about a miracle working god-man Jesus or any of the events described in the New Testament. How did they miss all the horrific events and miracles, to say nothing of the earthquakes, dead people walking around etc.
There are only passages that were later add on's and are clearly forgeries; the Christian Fathers who were familiar with the works of Josephus knew nothing of the passage about Jesus, and he was not a contemporary. Josephus was born in 37 CE, long after the supposed crucifixion of Jesus. A very good reason for scholars to say it is forgery is the fact that the Testimonium of Josephus claims Jesus is the messiah and it could only have been written by a Christian. Josephus was never a Christian; he was an orthodox Jew. But even if someone wants to believe Josephus wrote it; it would still only be hearsay. The Church fathers thought it was acceptable to conceal or fabricate evidence if it would help support their religion. Eusebius, a third-century bishop, openly stated that lying for the cause of Christianity was perfectly acceptable. Ignatius said, "To be right in everything, we ought always to hold that the white which I see, is black, if the Hierarchical Church so decides it."
Much of the Old Testament comes from Ugarit. The Ras Shamra texts prove the Old Testament came from texts discovered at Ugarit. They reveal that the patriarchal stories in the Old Testament were not merely transmitted orally but were based on written documents of Canaanite origin, the discovery of which at Ugarit has led to a new appraisal of the Old Testament.
There are actually millions of educated people around the world who have investigated religion and it's claims and do not believe religion is anything but myths. Many countries around the world have abandoned superstitious beliefs, and they are some of the happiest people on earth.