The True Shape of the Cross
The historical shape of the “true cross” that Jesus died on is not actually known. In fact, there are over four hundred variations of the cross in Christian art and symbolism. While Westerners are most familiar with the Latin style cross, which usually depicts two intersecting beams of unequal length, many ancient and medieval illustrations portray the act of crucifixion completely different from each other. Indeed, the Hebrew, Greek, and Latin term for “cross” simply denotes a stake on which someone could be impaled, hanged, tied, or nailed. Because of the sparsity of information in the Gospels, the manner of Jesus’ execution could have simply involved an upright vertical stake (crux acuta), a three-armed Tau or T-shaped cross, a Y- or (less likely) X-shaped cross (crux decussata), the Greek + cross of equal arm length, or the classical four-armed cross (crux immissa) seen in church statues and staffs today.
The most plausible design was the T-shaped cross (crux commissa) as argued in the first/second century Christian text, Barnabas 9.8, as well as suggested in the second century by Justin Martyr (Dial. 91.2). The T-shaped cross was, after all, the most common style and easiest to manufacture for the Romans. Indeed, it is likely that the Latin style design common today actually evolved out of the ubiquitous use of the chi-rho monogram (the Greek letter P overlaid onto the letter X), which was used for Jesus’ name in the ancient church. It became customary for early Christians to overlap the two letters to form a cross-like design (⳩). By the end of the fourth century, the chi-rho was replaced with a monogramatic cross of an inverted X to form the upright + shape, which was then overlaid onto the Greek P (rho). Eventually, at the beginning of the fifth century, the P was removed, leaving only the Latin-style cross in its wake.
Learn more about the history and philosophy of artistic depictions of Jesus' crucifixion in the book, Violence in Art.