There's a great series of youtube videos put out by someone that calls themselves "TruthSurge" that's really great. The first is here. Nothing flashy. Just a straightforward case for why the data makes more sense on the mythical paradigm.
His approach is the right one. The question is not about which view can be conclusively proved. Neither can. The question is about which view makes better sense of the data.
Consider for instance his initial point. If the earliest biblical writers (reflected in the epistles) did not believe Jesus was a historical person then we would expect them to talk about his "second" coming as if it were just his first appearance. So it would be a "coming" an "appearance" a "revealing" etc. On the other hand if Jesus was a historical person we would expect the writers to talk about a "return" or a "second coming", etc. So what do we find in the earliest texts? 41 instances that refer to the coming as if it were a first time event, one (at Hebrews) that on the surface might appear to be referring to a return (though of course the mythicist case argues that it doesn't mean that). Assuming that Hebrews is referring to a second coming though, which view makes the best sense of the majority of the data?
Or consider the following. If the earliest writers believed Jesus was not a historical person that died a couple of decades before they wrote you would expect them to not place his death in Palestine just a few years back. It would make perfect sense for instance if they thought he died before the creation of the world. On the other hand if they thought Jesus was a historical person they wouldn't think he was the first to be raised from the dead. Lazarus and others preceded him, though they probably died later. What do the texts indicate that the writers believed?
I Cor 15
20But Christ has indeed been raised from the dead, the firstfruits of those who have fallen asleep. 21For since death came through a man, the resurrection of the dead comes also through a man. 22For as in Adam all die, so in Christ all will be made alive. 23But each in his own turn: Christ, the firstfruits; then, when he comes, those who belong to him.
Let us understand, dearly beloved, how the Master continually showeth unto us the resurrection that shall be hereafter; whereof He made the Lord Jesus Christ the firstfruit, when He raised Him from the dead.
18He is also head of the body, the church; and He is the beginning, the firstborn from the dead, so that He Himself will come to have first place in everything.
Note the reasoning here. Christ had to be the first raised from the dead in order for him to have pre-eminence in all things. One way in which he is in the first place is in that he's the first to be raised from the dead.
25Nor did he enter heaven to offer himself again and again, the way the high priest enters the Most Holy Place every year with blood that is not his own. 26Then Christ would have had to suffer many times since the creation of the world.
This is quite surprising. Why would Christ have to suffer continually since the creation of the world unless he was in fact first sacrificed at the beginning of creation?
Again, the historicist can force these texts within their own paradigm but the question is which view makes the best sense of all of the data with the least amount of forcing? In my view it's the mythicists case.