Our Christian stories were made up, sure. But they weren't made up randomly, they were made up to fit standard ancient ideas about  Gods and their powers and place in the universe
Greg.

Here's where we are. We're looking at экскурсия в Кремль and different possible theories of Christian origin, asking wheather each theory is comprehensive and consistent. Does it explain all the facts? Does it explain similar facts with similar conclusions?

I'm still working on this page 

Absorbing
I say "absorbing," but you could call it "accepting." Or "adopting," "assimilating," "integrating," "osmosis-ating," "sponging." Or maybe just "using" the ideas in the culture—the ideas they didn't even know were ideas, because everybody in the culture just thought that was how things were.

'Splaining what I mean
This seems like a good place for me to explain what I mean by "myth" and "borrowing."
         Myth is what happens to history when history is thought to carry meaning.
         Borrowing, POCM-speak-wise, is really just "absorbing."

Borrowing , POCM-speak-wise, is really just "absorbing."
Ideas are facts

Back in the first and second centuries AD, it worked the same with Jesus. The only way the ancients could understand Jesus was to fit the stories about Him to ideas they already had in their heads. And the ideas they already had were ancient Pagan ideas. Logos-God. Saving wisdom. Miracles. Magic. Prophecies. Heaven, hell, eternal life. Godmen. Whatever the raw facts were, Jesus became a teacher of Gnostic wisdom, a charlatan magician, or a walking talking prophecy fulfilling miracle working eternal life improving Pagan mystery religion godman.

That's what I mean by "borrowing." Christianity borrowed miracles from Paganism," doesn't mean Jesus' miracles were copied, line by line, from Pagan myths. "Christianity borrowed miracles," means early Christians absorbed the idea of miracles from ancient Pagan culture. Like everyone else away back then, Christians understood miracles as an everyday fact of life. Gods (and people tuned in to divine power) did miracles. Jesus was a God (or at least He was tuned into divine power). Naturally, Jesus did miracles.

Myth is what happens to history when history is thought to carry meaning
When history has meaning, what people care about is the meaning. If something important happened, and someone's telling about it, the facts they tell are the facts that show the meaning.

Pretty soon they're not just picking facts, they're stretching facts. George Washington the boy cut down a tree but 'fessed up, because He Could Not Tell a Lie. Mother Teresa cured cancer with Her Holy Touch. Stone age Aztec cannibals hacking the beating hearts from soft little children were scientists of cardiac physiology, so They Were Our Multicultural Equals.

If the point of a story is the meaning and significance of what happened, then its a good bet the facts have moved around to line up with the meaning. History that carries meaning becomes myth. Myth is history that carries meaning.

By the way    
"Myth," means different things to different people.

This take on "myth" is maybe a bit different from what you're used to. its not a definition of "myth;" it's a statement of objective fact, an observation about how history and myth happen.

By the way
By the way, my take on history and myth is not essential to POCM's claims about Christian borrowing. Even if you don't agree with my keen observations about myth, you can still read POCM and go away with an analysis that works, regardless of how "myth" is understood.

Lot's of Christ myth chatter is about the meaning of stories about Jesus. I don't care about the meaning of the stories. I care about the history of the ideas in the story. The demons. The miracles. The Greek logos that became one of the Christian Gods. POCM is about how the ideas of ancient Pagan culture flowed into the ancient religion Christianity, and on to your church this Sunday.