I haven’t read the whole site, but the page you pointed to is the atheist equivalent of Christian conspiracy theorists. We know a lot about the history of Christianity. Most of the claims of pagan borrowing are bunk: Here’s a good rebuttal of one of the more common ones:
http://tektonics.org/copycat/mithra.php. (I don’t agree with much of the theology on Tektonics, but this particular posting seems to be a good source.)
Does that mean there’s no influence? Of course not. Christianity in the 1st Cent was influenced by the surrounding culture, just as it is today, but not in quite such an overt way. Some of the influences:
* The terms used in defining the Trinity and Incarnation certainly come from Greek philosophy. That’s not a surprise, of course, since that was the most sophisticated philosophy known at the time.
* The term “Gospel” and “good news” seems to have been used by the adherents of Caesar, referring to announcements of various triumphs of Caesar. Hence Jesus’ use of the term can reasonably be viewed as confrontational, as a direct challenge to the claims of Caesar.
* Claims that Jesus’ resurrection is a pagan knock-off vanish when you start looking at the supposed parallels more closely. But rebirth, both literal and spiritual, is certainly a common theme in religions and philosophies. So are things like judgement after death and some kind of afterlife. Indeed those are present in Judaism, which is the most convincing background for Christianity.
Other parts of the site are too absurd to bother with. I particularly liked the treatment of 9/11. What that has to do with magic in the Bible (which was the title) I have no idea.
The articles on communism are interesting. It is quite true that Christianity is community-oriented. US Christianity has at times tried to turn Christianity into “just me and Jesus,” seeing it as just a way for individuals to avoid hell. But in fact Jesus said he was coming to found the Kingdom of God, a community of followers of Jesus. Jesus trained a community of followers, and Acts clearly shows the early days of the Christian community. The problem with Russian communism wasn’t that it was community-oriented, but that it was based on ideas of human behavior that didn’t work (that if the State took over the economy, selfishness would magically disappear), and that it turned totalitarian. Jesus certainly didn’t advocate a totalitarian State. His Kingdom had him as king, although at times Christian leaders have tried to take that authority for themselves. Being a Christian doesn't require you to accept right-wing American politics. Christians can certainly believe that we have a responsibility to deal with the poor and other powerless people. The Prophets were clear about that, as was Jesus. The question, however, is what approaches do that best. Communism is pretty clearly a failure.
Note the anti-Semitic, conspiracy-theory orientation of the site. That should clue you in to the unreliability of the information there.
There are certainly reasons why good people sometimes find Christianity hard to believe. I’d be happy to talk with you about them. But that site isn’t a useful place to start.
