We just learned about the symbols Alpha and Omega.
Another Christian symbol is the Staurogram, which is like the letter P crossed with the letter T.
It comes from the greek word stauros (σταυρός), which means cross.
When you say the letters tau (τ) and rho (ρ) together as tau-rho it almost sounds like stauros, so that was a way to make a symbol of the tau and rho to mean stauros.
Some people think it also looks like Jesus on a cross.
(from: wikipedia - staurogram)
Kid Facts - Blast from the past: The Apostles Persecuted