There are so many delusions to mention that it's hard to choose just ten, and it's hard to rank them since they're all equally delusions. But in keeping with David Letterman's series of top ten lists here they are for your enjoyment:
10) That Ex-Christians like me were never Christians even though we believed and trusted in God for salvation. So let me get this straight, okay? God supposedly promised that if we believe we'll be saved and yet even though we believed we were never saved!? Such logic as this is the logic of a delusion.
9) That Christianity has more credibility to it than Scientology, Mormonism, Islam, Orthodox Judaism or Haitian Voodoo. The only reason Christians think their faith has more epistemic warrant is because they are more familiar with it.
8) That there was a person who was 100% God and 100% man with nothing left over who walked the earth even thought the Bible itself tells us ancient people believed demigods walked the earth. Just look at Acts 14:11: "When the crowd saw what Paul had done, they shouted in the Lycaonian language, 'The gods have come down to us in human form!'" And, Acts 28:5-6: "Paul shook the snake off into the fire and suffered no ill effects. The people expected him to swell up or suddenly fall dead, but after waiting a long time and seeing nothing unusual happen to him, they changed their minds and said he was a god."
7) That a demigod or God-Man atoned for the sins of the world even though there is no reasonable way to understand how his death brings us forgiveness. Ken Pulliam has written the most extensive online material about this irrational doctrine with 88 posts so far.
6) That even though the Apostle Paul was the only NT author to claim he saw the risen Jesus, Paul said he merely saw a vision of Jesus on the Damascus Road rather than Jesus himself. Yep, just see Acts 26:9: "So then, King Agrippa, I (Paul) was not disobedient to the vision (i.e. ὀπτασίᾳ) from heaven." That's called evidence? I hardly think so at all. This kind of evidence would support the claims of Joseph Smith, Mohammad, Jim Jones and almost every other religious leader.
5) That the highest created being, known as Satan or the Devil, led an angelic rebellion against an omnipotent omniscient omnibenelovent omnipresent God, and expected to win--which makes Satan out to be pure evil and dumber than a box of rocks.
4) That there was a first human pair (Adam & Eve) who so grievously sinned against God when tested that all of the rest of us are being punished for it (including animals), even though no one but the first human pair deserved to be punished. If it's argued that all of us deserve to be punished because we all would have sinned, then the test was a sham. For only if some of us would not have sinned can the test be considered a fair one. But if some of us would not have sinned under the same initial conditions then there are people who are being punished for something they never would have done.
3) That although there is no cogent theodicy that can explain why there is such ubiquitous and massive human and animal suffering if a perfectly good omnipotent God exists, God is perfectly good and omnipotent anyway.
2) Let me quote someone named SilverBullet who wrote: “...the lord doesn't work in mysterious ways, but in ways that are indistinguishable from his non-existence. It seems to me that there is nothing in the Christian scriptures, no sentence, paragraph, or idea, that couldn't be anything more than the product of the humans alive at the time that the apparently divinely inspired scriptures and ideas were "revealed".
1) That when it comes to verifiable matters of historical fact (like the Exodus, the extent of the reign of David, Luke's reported world-wide census, etc) the Biblical stories are disconfirmed by evidence to the contrary as fairy tales, but when it comes to supernatural claims of miracles that cannot be verified like a virgin birth and resurrection from the grave, the Bible reports historical facts.
Some of these were chosen from my list of 30 items I called a Reality Check: What Must Be the Case if Christianity is True?