The Sacrifice of Isaac
West portal, St. Peter's Cathedral, Regensburg, Germany
The image is mostly a literal rendition of Genesis 22:1-19, picturing the boy, the ram, and the angel staying Abraham's hand. But Christian writers took the all-but-sacrifice of Isaac to prefigure the completed sacrifice of Christ on the Cross. For this reason, this and most other Christian images of the episode make the altar resemble those used in the Mass, which is a memorial of the sacrifice of Christ.
The monstrous figures adorning the column's four corners may be coincidental or may represent the dangers from which the sacrifice saves the Christian.
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More of Abraham
Photographed at the cathedral by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.