In is Second Letter St. John wrote about the deceivers who do not acknowledge that Jesus came in the flesh.
The first heresy to hit Christianity featured would-be-Christians who just could not picture Jesus with a need to relieve himself, or with bones that grew weary; but John, in his story of the Samaritan woman at the well, had told us that Jesus was weary, needing to rest while he sent the Apostles into town.
Six centuries before Christ, the Persian leader Zoroaster had a large segment of the Middle East believing in two creators, a good one who created our souls, and an evil one who created our bodies. Many people, without buying into that religion, went along with viewing our human bodies as not quite nice.
Those people began saying that the body of Jesus was a mirage that accompanied his great soul. With the Greek word for a mirage being a dokein, it began to be the custom to refer to such people as Docetists. Some old religious movie-makers used to picture Jesus as something like a walking spook.
The evil in Docetism is that it took away the meaning of the suffering Jesus did for us, turning it into a mirage that really didn’t hurt.
No, Jesus heroically put up with suffering such as you and I could not endure, and he did it for love of us. Like the song says, “No, no, no. You can’t take that away from him.”