Christian symbols

Christian symbolism is the use of symbols, including archetypes, acts, artwork or events, by Christianity. It invests objects or actions with an inner meaning expressing Christian ideas.

The symbolism of the early Church was characterized by being understood by initiates only, while after the legalization of Christianity in the 4th-century more recognizable symbols entered in use. Christianity has borrowed from the common stock of significant symbols known to most periods and to all regions of the world.

Christianity has not generally practiced Aniconism, or the avoidance or prohibition of types of images, even if the early Jewish Christians sects, as well as some modern denominations, preferred to some extent not to use figures in their symbols, by invoking the Decalogue's prohibition of idolatry.

The shape of the cross, as represented by the letter T, came to be used as a "seal" or symbol of Early Christianity by the 2nd century. At the end of the 2nd century, it is mentioned in the Octavius of Minucius Felix, rejecting the claim by detractors that Christians worship the cross. The cross (crucifix, Greek stauros) in this period was represented by the letter T. Clement of Alexandria in the early 3rd century calls it τὸ κυριακὸν σημεῖον ("the Lord's sign") he repeats the idea, current as early as the Epistle of Barnabas, that the number 318 (in Greek numerals, ΤΙΗ) in Genesis 14:14 was a foreshadowing (a "type") of the cross (T, an upright with crossbar, standing for 300) and of Jesus (ΙΗ, the first two letters of his name ΙΗΣΟΥΣ, standing for 18).

...
Wikipedia