Is Christianity based on older myths?

[Minimalist]

In 160 Ad Justin Martyr wrote his apologia to Emperor Antoninus Pius. In this entire lengthy work he does not mention any Paul even once. This in spite of the claim that Paul brought xtianity to the Romans a century earlier.

There are big fucking problems with the Paul story.

I find it humorous that you use Justin Martyr as a source for Paul's non-existence.

1. Justin Martyr's works did not all survive.
2. In his surviving writings, he did refer to the "memoirs of the apostles" (gospels-plural) multiple times. He believed them to be reliable, and lastly,
3. The following quote suggest you are just wrong.

Reflecting his opposition to Marcion, Justin's attitude toward the Pauline epistles generally corresponds to that of the later Church. In Justin's works, distinct references are found to Romans, 1 Corinthians, Galatians, Ephesians, Colossians, and 2 Thessalonians, and possible ones to Philippians, Titus, and 1 Timothy. It seems likely that he also knew Hebrews and 1 John. The apologetic character of Justin's habit of thought appears again in the Acts of his martyrdom, the genuineness of which is attested by internal evidence.[43] http://en.wikipedia.org/wiki/Justin_Martyr

Other early church writers have told us what Marcion said and what his 'canon' comprised: 10 epistles of 'paul' and a truncated version of luke.

What is at issue is the persona of this 'paul' character who no one seems to know about until after Marcion is denounced as a heretic.

We know that "luke" was grabbed by the proto-orthodox and fleshed out to make it conform to the rest of their bullshit. It seems likely that the "paul" letters were also salvaged and redone. Remember that we have only the versions which the proto-orthodox put forward. We have not a single clue about what the original documents might have said.
For all you know, they could have said that "jesus would not be some smelly jew" because that would be in keeping with Marcion's p-o-v.

When you can stop treating this bullshit as somehow 'inspired' then you may be able to look at them critically. I have little hope that you will ever demonstrate that ability.