I've read a couple articles on Richard Carrier's website about the Christ Myth Hypothesis. And he basically stubbornly says that the differences like what InspiringPhilosphy and Chris White point out don't matter, it's only the similarities that matter.
[Update August 17th 2018: I need to add a major qualifier to my endorsement
of Inspiring Philosophy's Copycat Savior playlist since in the new
Inanna video he engages in the massive Hersey of denying The Harrowing
of Hell.]
Well it's nice that you feel you get to write the rules of this debate in a way that inherently favors your side. But if you took George Lucas to court for plagiarizing The Hidden Fortress in Star Wars Episode IV: A New Hope and said "all these differences don't matter" the Judge would laugh at you. "No one is claiming Star Wars is a true story" you might respond, well things that actually happen sometimes seem like history repeating itself, there were a lot of jokes back in the 2000s about a second George Bush starting a second war with Iraq. And sometimes things that actually happen seem like earlier fiction coming true, which is a recurring meme about our current President, fictional Donald Trumps got into the White House long before the real one did, and in most cases those writers thought they were writing an inherently impossible absurdity. Or I could leave politics out of this and point to The Wreck of the Titan: Or, Futility.
Christianity has never claimed to base it's credibility on saying no one had ever thought of the idea of coming back from the dead before. Quite the contrary I seek to show that the idea was firmly set up by the Hebrew Bible, including The Torah, in Genesis 22 and Joseph's narrative, and some of the Psalms. And everything that's a basis for the Messiah Ben-Joseph tradition. And the general Resurrection of the Dead was foretold in Isaiah 26, Ezekiel 37 and Daniel 12.
Richard Carrier is unique, he brings up his beliefs about the Old Testament not being much different from Pagan beliefs either in the same articles he talks about the Christ Myth Hypothesis. You see lots of Christ Mythers are doing this partly with an agenda of denying the Jewishness of the New Testament, of saying it uses the situation of First Century Judea as a setting but that it's fundamentally philosophically Greco-Roman. And that attitude is what I'm trying to oppose in posts like Greek words that are viewed as Gnostic and The Hebrew precedent for the Last Supper.
For example, people who see Virgin Births in every ancient Pre-Christian special birth story BUT Isaiah 7:14. Saying "Isaiah couldn't possibly have been talking about a Virgin Birth because his said Almah not Bethulah", and then turn around and read Virgin Births into Greek stories that never called anyone a Parthenos and do graphically describe sexual intercourse.
One website I read went on about how "Goddesses aren't like Humans, we can assume they remain Virgins even when they have sex", as if the "Hyman" was the point. Only three Olympian deities are called Virgin as a title and none of them reproduced, likewise with the non Olympian Astraea. And in the Ugarit texts only Anath is called any word for Virgin and she never reproduced either, one line in the Baal Cycle can be taken out of context about her "Bearing a calf" but that was about her carrying one in her arms not giving birth. The Egyptian Virgin Goddess was Nephthys, who Wikipedia says was the mother of Anubis but there is no actual solid source on that. Isis was never ever called a Virgin until post Enlightenment Thesophists and Neo-Pagans decided it suited them to do so.
If the Christ Mythers stated this part of their argument as just being that there were miraculous births before Jesus, it wouldn't be so easy to nit pick it to death. But they don't do that, the names of their articles and blog posts are always about Virgin births. But you see they know deep down only calling it a "Virgin" birth is specific enough to be an impressive similarity.
However I'm not as invested in the uniqueness of the Virgin Birth as I am the Resurrection, because the Virgin Birth isn't the definition of The Gospel, The Resurrection is. And that is where I'll firmly respond to Carrier's attitude by saying that to me the similarities don't matter, because the difference between Jesus Resurrection and pagan Dying and Rising god myths is where the definition of The Gospel lies.
Pagan dying and rising god myths are mere allegories for the "Circle of Life", meant to reinforce that Death is a natural part of how the world works that we need to accept. Which is also the Moral of the Epic of Gilgamesh. You see these Pagan "dying and rising gods" don't permanently rise, Osiris winds up right back down in the Underworld after being reanimated just long enough to conceive Horus. After the Sermon on Mars Hill in Acts 17 the Greek audience is baffled by Paul's declaration of The Resurrection, not because the author of Acts was unaware of Greeks myths that could be called dying and rising myths, but because Paul is referring to someone who stayed Risen.
The Harrowing of Hell doctrine gets compared to Orpheus traveling to Hades, but Orpheus failed, like Izanagi failed, however Jesus succeeded in getting His Bride out of Hades. The stories of Orpheus and Izanagi are the Bad News, they send the message that there is no escape from Hades/Yomi. Paul proclaimed in 1 Corinthians 15:55 that Death has no Sting and Hades has no Victory. Revelation chapter 20 foretells that Hades will one day be emptied. And in my interpretation of Scripture it's not merely some Humans who will be risen to Eternal Life, it is all of us, because I believe in Universal Salvation.