Schizophrenia often involves hearing voices, doesn't it? Yet Jesus rarely if ever claims to hear a voice from heaven telling him what to do. His messianic delusion could be explained by narcisissm without any resort to more exotic mental maladies.
I do think that a great deal of the words coming out of Jesus' mouth were attributed to him by later writers in order to explain how he was going to come back, after being unexpectedly executed, or to position the early church in some way (like the warning about false messiahs, to avoid a takeover of the religion by someone claming to be Jesus redivivus).
Even his statements against the Pharisees could be seen as dubious in light of the fact that his execution is blamed on the Pharisees even though the Romans executed him. I think someone (Paul?) wanted to shift the blame to the old Jewish system, for a reason I can only guess at. All those times that Jesus is scolding the over-scrupulous Jewish leaders could be just another way of emphasizing what Paul taught when he wrote that the Law has passed away thanks to Jesus, and that the old way of thinking was obsolete.
Paul's message was the one that caught on, not the more orthodox Jewish message coming out of Jerusalem, so I don't find it far-fetched that the gospels were modified, perhaps after the "Jewish Armageddon" of 70CE, to place words in Jesus' mouth which condemned the (recently moribund) old Jewish system of things. The enlightened response of the pericope adulterae could well be just another propagandistic renouncement of the old Jewish laws, inserted retroactively into Jesus' teachings in order to shift the paradigm away from the failed older versions of Christianity that were either killed off in 70CE or suppressed by the Romans for being too brutal or too anti-state.