It is somewhat ironic that the oldest known depiction of the crucifixion of Jesus comes from Rome, and its in the form of a grafitto that mocks a follower of Jesus. This grafitto was discovered in a room on Palatine Hill (the area of the palaces of the Roman emperors) around 1856. It dates to about AD 200. The inscription features two characters: a soldier who has a hand raised in worship, and a donkey-headed figure on a cross.

Figure of Alexamenos with a hand raised in worship; photo by Kris Udd
To the Roman mind, the idea of a crucified God was scandalous. Of course, this idea was also difficult for the Jewish mind to accept.

Donkey-headed figure on a cross; photo by Kris Udd.
The brief inscription that accompanies the characters on this grafitto is in Greek and reads, “Alexamenos worships his God” (ΑΛΕΞΑΜΕΝΟϹ ϹΕΒΕΤΕ ΘΕΟΝ). The photo below shows the entire grafitto, and the photo after that includes highlights to help pick out both the figures and the inscription.

Alexamenos grafitto with inscription; photo by Kris Udd
This is the inscription with the figures and text highlighted.

Alexamenos grafitto with figures and text highlighted; photo by Kris Udd
There is no religion other than Christianity that worships a crucified Savior, leading to the obvious conclusion that both the “God” referred to in the inscription and the crucified figure were meant to portray Jesus Christ.
Why is this significant? It illustrates the centrality of the crucifixion, a suffering Savior, to Christianity at a very early period. This reflects the very first sermon preached by Peter, in which he carefully described Jesus in this way. “This Man, delivered up by the predetermined plan and foreknowledge of God, you nailed to a cross by the hands of godless men and put Him to death. And God raised Him up again, putting an end to the agony of death, since it was impossible for Him to be held in its power” (Acts 2:23-24). He repeated this message before the Sanhedrin, “The God of our fathers raised up Jesus, whom you had put to death by hanging Him on a cross. He is the one whom God exalted to His right hand as a Prince and a Savior, to grant repentance to Israel, and forgiveness of sins” (Acts 5:30-31). Paul’s message was similar, such as when he spoke in the synagogue at Pisidian Antioch, “And when they had carried out all that was written concerning Him, they took Him down from the cross and laid Him in a tomb. But God raised Him from the dead” (Acts 13:29-30). This same message must have continued to be faithfully retold, since that was the focal point even of those ridiculing Christians at the end of the 2nd century.
It may be worth noting that a suffering Messiah was anticipated much earlier, in the Hebrew Bible. David spoke of this when he said, “You lay me in the dust of death . . . they pierced my hands and my feet. I can count all my bones; they look, they stare at me, and they divide my garments among them, and for my clothing they cast lots” (Ps 23:15-18). Isaiah was even bolder in proclaiming, “He was cut off from the land of the living for the transgression of my people, to whom the stroke was due. His grave was assigned with wicked men, yet he was with a rich man in his death, because he had don no violence, nor was any deceit found in his mouth” (Isa 53:8-9).
Today this inscription is housed in the Palatine Hill Museum. It is mounted behind glass on a well-lit wall, but at the time of my visit (June 2023) it had no signage whatsoever to identify it, and the museum staff I asked for direction was unaware of its existence.
For discussion of the peculiar spelling of the Greek word “worship” (Gk. ΣΕΒΕΤΕ) see the short article by Rodney Decker.