Alpha and Omega
Alpha and omega are the first and last letters of the Greek alphabet, signifying that God is "the beginning and the end," or eternal. The symbols were used in early Christianity and appear in the Roman catacombs.
In Rabbinic literature, the word emet ("truth"), composed of the first and last letters of the Hebrew alphabet, is "the seal of God," and in Judaic tradition it carries somewhat the same connotation as Alpha and Omega.
The Alpha and Omega symbols are often combined with the cross, chi rho, or other Christian symbols.
Related Bible Verse
"I am the first and the last" (Isa. 44:6)
"From everlasting to everlasting thou art God" (Ps. 90:2)
"I am the Alpha and the Omega," says the Lord God, "who is, and who was, and who is to come, the Almighty." (Rev 1:8, NIV)