The Crucifixion
The Christian account of the crucifixion as the human sacrifice that atones for humanity's sins.
In Christian doctrine, the atonement of sins is accomplished through human sacrifice — specifically, the sacrifice of a sinless human being, Jesus (peace be upon him). This act of offering is what’s referred to as the crucifixion. Below is a verse from the Gospel of John describing part of the event:
ὁ οὗν πιλᾶτος ἀκούσας τῶν λόγων τούτων ἤγαγεν ἔξω τὸν ἰησοῦν... ἐκραύγασαν οὗν ἐκεῖνοι, ἆρον ἆρον, σταύρωσον αὐτόν. “...and carrying the cross by himself, he went out to what is called The Place of the Skull, which in Hebrew is called Golgotha. There they crucified him, and with him two others, one on either side, with Jesus between them.”
A complete description of the event, according to the Gospels, can be found in John 19:17-30, Matthew 27:33-50, Mark 15:22-37, and Luke 23:32-49.
Muslims do not accept this account of Jesus’s death — for the Muslim view of what happened, and why the crucifixion isn’t required for forgiveness, see Atonement of Sins and Sin in Christian Thought.