The letters are not 'P' nor 'X'. This symbol - a very ancient secret symbol of Christianity is known as the 'Chi-Rho' sign. It was used, along with an anchor and a fish as secret symbols used to identify Christians if two people met secretly, during the time in the early Church when being identified as a Christian meant almost certain death in the Roman arena fighting gladiators or lions. These letters are actually the Greek letters 'Chi' χ and 'Rho' ρ These two letters were the first two letters of the name 'Christos' (Ch + R) meaning 'Christ'. Nowadays the ChiRho signis used throughout churches as a Christian symbol, much in the same was as a fish or even a cross.
Literally? No. Figuratively? It's a ritual to symbolize such.
baptism
Baptism is often represented by a scallop shell
It symbolizes goodness, and the start of a new life.
It symbolize the cleanliness of the soul or pure.
They mean you are tough. =-P
S. P. Lowe has written: 'Infant baptism' -- subject- s -: Accessible book, Apologetic works, Infant baptism, History
Water is used in baptism to symbolize the cleansing from sin given by the free grace of God.
The scallop shell can represent the sacrament of Baptism or it can also represent St. James the Greater.
P. B. has written: 'A discourse of baptism: or an answer to Mr. Stubs's sermon ... to Mr. Dorrington's Vindication of baptism; and to a discourse of the late Mr. Nat. Taylor. By P. B. ..' 'Christianity revived, and judaism subverted'
4p
p2 X p2 = p4or p X p X p X p = p4