In an article for the Deseret News, "Defending the Faith: 'Parallels' of prophets not parallel," explains that this assembly of parallels, now found in many sources in print and on the web, ultimately derives from a single source: "The World's Sixteen Crucified Saviors: Christianity Before Christ," an 1875 book by an American atheist named Kersey Graves. The book in several forms is available at Archive.org. With no references cited, Graves simply declares that extensive parallels exist between the details of Jesus Christ and numerous other ancient deities, showing, he claims, that Christianity was simply made up, swiping concepts already out there. The virgin birth, His status as Son of God, the miracles, the teachings, the Crucifixion, the Resurrection, etc., all are allegedly plagiarized from Mithra, Osiris, Baal, etc. And it's all nonsense, Peterson explains. In many cases Graves is simply making stuff up, creating parallels that aren't really there. Sad that some have lost their faith over such stuff.
Yes, there are interesting parallels between religions, and as Latter-day Saints, we understand that many ancients including Book of Mormon writers had teachings about the future Messiah who would come as Son of God, be slain, and rise again. The theme of ascending to God is an important one in the ancient world, and we should not be surprised to find scattered parallels between our faith and many other faiths. See, for example, The Sacred and the Profane by Mircea Eliade. Properly understood, the parallels that actually do exist can be meaningful and can help us better appreciate other faiths and the possibility of some common ancient roots. But when it comes to the extreme parallels that are used to declare Christianity a fraud, the real basis for fraud is in the fabrications from Kersey Graves. His undocumented allegations are not to be trusted at all.
One resource for exploding the bogus parallels against Christianity is "Evidence for Jesus and Parallel Pagan 'Crucified Saviors' Examined" by Philip J. Porvaznik. Gets into the details of each of the alleged 16 crucified saviors of pagan lore. Interesting.
Don't be the next victim of bogus parallels undermining Christianity, including LDS Christianity. Parallels, like scientific data, can be meaningful when the right questions are asked and the right tools are applied. But when the data are simply fabricated or twisted beyond recognition, look out.