Maybe Jesus was not who He claimed to be
There have been lots of people throughout history who have claimed to be the Messiah, or to be the Son of God, and the like. Some of them started movements and built huge followings while claiming to have "higher wisdom" or an understanding of the Whole Truth.
Maybe the Biblical record was kept by people who were not impartial. Perhaps they had an agenda and only wrote things that advanced their plan, embellished if necessary, and left out anything derogatory.
Some of the miracles recorded are unbelievable. I find it hard to believe anyone could actually walk on water.
There are other explanations for the resurrection: he passed out but wasn't really dead, or they actually crucified someone else, or they went to the wrong tomb on Sunday, or maybe the disciples really did steal the body.
Jesus just isn't what I'd expect from the Son of God. If Prince Charles announced that some day he would be king, it would be believable. If some common person from a place you never heard of said the same thing, you would doubt it. I guess it's the same with Jesus - if he really was the Son of God, I would expect that the gospel records would read much differently. He would have had better friends and would have made a much greater impact on the world.