https://historyforatheists.com/2016/12/the-great-myths-2-christmas-mithras-and-paganism/ This site has a great breakdown and take down of the most popular atheist "myths" about religion. Religious stories and arguments collapse on their own lack of merits; there's no need to make up bad history to try to debunk or discredit them. Movies like Zeitgeist are not helpful, and if anything end up poisoning the well by making objections to religion look weak and fallacious.