But if it is preached that Christ has been raised from the dead, how can some of you say that there is no resurrection of the dead?
(1 Corinthians 15:12)
If there is a point in all Paul that may be defined evidence of the historicity of Jesus, it is this. If the deniers of the resurrection ("some of you") are Christians, i.e. people who by definition believe that Jesus is someway a divine being, then they can only be separationist Christians: Jesus died and didn't rise, while the spiritual Christ didn't suffer (hence he can't be said 'risen'). Hence it is improbable that the body of Jesus was left in the tomb in the lower heavens, while the Christ didn't die in the his place. A Jesus who dies and doesn't rise (while the Christ doesn't suffer) is clearly an earthly Jesus. Separationism is intrinsically an earthly christology.
I think that only if "some of you" are not-Christians, only in that case, the passage can be expected under mythicism.
Unfortunately, I don't see as Doherty addresses this problem, even if he enumerates 15:12 among the surprising silences:
1 Corinthians 15:12-16
12But if it is preached that Christ has been raised from the dead, how can some of you say that there is no resurrection of the dead? 13If there is no resurrection of the dead, then not even Christ has been raised. 14And if Christ has not been raised, then our preaching is vain, your faith also is vain. 15Moreover, we are even found to be false witnesses of God, because we witnessed against God that he raised Christ, whom he did not raise if in fact the dead are not raised. 16For if the dead are not raised, not even Christ has been raised. [NASB/NIV]
There are some devastating implications to be drawn from this passage. Paul expresses himself as though the raising of Christ from the dead is a matter of faith, not of historical record as evidenced by eyewitness to a physical, risen Jesus at Easter. He is so adamant about the necessity to believe that the dead will be raised, that he is prepared to state—and he repeats it four times—that if they are not, then Christ himself "has not been raised." If men he knew had witnessed the actual return of Jesus from the grave, I do not think he would have thought to make even a rhetorical denial of it.
Moreover, the verb for "witness" (martureo) is often used in the sense of witnessing to, of declaring one’s belief in, an item of faith, not of factual record (though it can mean this in some contexts). Such a meaning here is strongly supported by what follows this verb: kata tou theou, or "against God." Translators often seem uncertain of the exact import of this phrase, but Bauer’s Lexicon firmly declares it as meaning "give testimony in contradiction to God." The idea that Paul is trying to get across here is that if in fact God did not raise Jesus from death (which would have to be the conclusion, he says, if all of the dead are not raised) then, rhetorically speaking, he and other apostles have been contradicting God and lying about Jesus’ resurrection.
The point is, and it’s unmistakable, Paul is saying that knowledge about Jesus’ raising has come from God, and that his own preaching testimony, true or false, is something which relates to information which has come from God—in other words, through revelation. Not history, not apostolic tradition about recent events on earth. In all this discussion about the trueness of Christ’s resurrection, Paul’s standard is one of faith, faith based on God’s testimony—meaning, in scripture. (Cf. Romans 8:25, 10:9, 1 Thess. 4:14.) Historical human witness plays no part.
http://www.jesuspuzzle.com/jesuspuzzle/siltop20.htm