You are reasoning in a circle, yes? Do you have any other reasons for thinking he is alive, other than reasoning in a circle and saying you know he is alive because he is alive?
Being closed to something that could not possibly be otherwise is one thing. Being closed to something that could possibly be different than what you think is quite another thing. I do not see how you can look at the sparse evidence we have about Jesus and say you could not possibly be wrong.
May I ask you how you know the external world is real? All your knowledge comes from your senses. Is it not possible your senses are deceiving you?
I admit the possibility that the external world is not real is so unlikely, we need not waste another second thinking about it. But we cannot be absolutely certain that it is real. Perhaps our senses are deceiving us.
Believing something for good reason is good, yes. But refusing to accept the possibility that one might misunderstand is not good, in my view.
And yet all your confidence is based on Paul, who doesn't even clearly testify to a bodily resurrection, and the four gospels, which were written significantly later by unknown writers who do not identify themselves or name their sources. Further, these books contradict each other. Yet based on this, you know that they are correct even when claiming something as unlikely as a resurrection?
Why not? Josephus reports a man who survived crucifixion.
Why I Don't Buy the Resurrection Story: Probability of Survival vs. Miracle - Assessing the Odds .
If you know nothing about a man other than that he was crucified, what are the odds he survived? 1 in 10,000?
If you know nothing about a man other than that he was crucified and died, what are the odds that he rose bodily from the dead 3 days later? 1 in 1,000,000,000,000?
Or maybe they were mistaken about where the body was. Or maybe Joseph of Arimathea did it on his own. Or maybe the legend grew up later.
Why not? That is what the Roman's always did with the bodies. How do you know the gospel story did not come later?
OK, but why squander a life on a story before making sure the story is true?