The basic, number one problem with Jesus is that he failed to write his own Gospel. Biblical scholars are unsure of who Matthew, Mark, Luke or John really were. Luke and Mark are Roman, not Hebrew names, and then Paul took over the Christian movement and began recruiting pagans and gentiles.
The Gospels contradict one another, which you can read all about by googling 'gospel contradictions'. And somehow, the year of Jesus' birth is only referred to very vaguely.
People who predict the future kinda sorta need to be more exact about the time their prediction is to take place.
Was Jesus even literate? He is referred to a Rabbi, and there is the scene with the scholars in Jerusalem, but their names or ranks are not given.
Muslims are strangely PROUD that Mohammad was illiterate, because they think that proves that everything he said came from listening to Allah rather than from reading books. But no one questions that there really was a real Mohammad, and there are many who question the existence of Jesus.