The ancient IHS / JHS symbol permeates Christian art all over the world.
Dating from the third century, Christians shortened the name of Jesus by only writing the first three letters of his name in Greek, ΙΗΣ (from his full name ΙΗΣΟΥΣ). The Greek letter Σ (sigma), is written in the Latin alphabet as an “S,” resulting in the monogram being commonly represented as ΙΗS or JHS.
The crossed keys are a symbol of Saint Peter's holding the keys to the worldly Church along with the image of the three small nails symbolizing the three which pierced Jesus's hands and feet.
