Chi Rho - This monogram superimposes the first two letters of the Greek word for Christ, ΧΡΙΣΤΟΣ. This symbol became widely popular after the Roman Emperor Constantine I adopted it for his vexillum, a flag-like military standard.
Alpha and Omega -“I am the Alpha and the Omega,” says the Lord God, “the one who is and who was and who is to come, the almighty.” If you're unfamiliar with Greek letters, you may not realize that the Greek symbols for “Alpha” (α or Α) and “Omega” (ω or Ω) are very prevalent in Christian art.
Pelican - Some legends claimed that when food becomes scarce a mother pelican will bite at her own breast until she draws blood. The mother will offer up her own blood to feed her babies rather than see them starve. The pelican became a symbol of the Passion of Jesus and the Eucharist.
Peacock - Ancient Greeks believed the flesh of a peacock did not decay after death. When Christianity spread through Greece, the peacock became a symbol for everlasting life.
Anchor - A symbol of safety, anchors were adopted by early Christians as a symbol of hope for the future. Christ is the unfailing hope of all who believe in him and the anchor of one's faith.
Ichthys - This early Christian symbol gained popularity due to a famous acrostic consisting of the initial letters of five Greek words – Iησοῦς Χριστὸς Θεοῦ Υἱὸς Σωτήρ, meaning “Jesus Christ, Son of God, Savior” – which taken on their own form the word for fish (Ichthus).
Shamrock - The shamrock is said to have been used to illustrate the Christian doctrine of the Holy Trinity by St. Patrick in the 5th century. The small clover plant creates a short,but expansive bed and the stems produce three leaves, which signify the Holy Trinity.