One way that is still used to denigrate and mock Christianity, as well as the ancients and medievals, is the suggestion that, prior to Columbus, everyone thought the Earth was flat. This belief was rooted in religious dogma and was therefore unchallengeable until it was demonstrated empirically to be false; and even then many people continued to affirm it. It is held up as a primary example of the folly of religion in contrast to the wisdom of science.

One of the common claims regarding Christianity and science is that scientists have been put to death for their scientific discoveries when they conflicted with the Church's teachings. This turns out not to be the case: no one has ever been put to death for their scientific claims in Western Europe. Two people that are often brought forward are Hypatia of Alexandria and Giordano Bruno. Hypatia was recently the subject of a movie which portrayed her as a pagan scientist towards the tail end of the ancient world, who was murdered by Christians. The suggestion is that when Christianity took over, the Dark Ages began, "dark" because the Christians rejected science. This, however, ignores the fact that Hypatia's murder was entirely political in nature, not religious or scientific. Michael Flynn, the science-fiction author has recently written an excellent series on Hypatia entitled "The Mean Streets of Old Alexandria". Here are the links:

(reposted from Agent Intellect)

It is well-known that people who lived before the Enlightenment were hopelessly superstitious. They believed, for example, that "odd" occurrences in the sky were omens signifying that odd occurrences would soon happen down here on Earth. The most blatant example of this took place when Halley's Comet appeared in 1456. While it was still visible, the siege of Belgrade by the Turks began; thus it was feared that this portent in the heavens had some relevance to the battle. Halley's Comet so upset Pope Callistus III that he resorted to drastic measures: he excommunicated it.