This design is also called a staurogram or monogrammatic cross.  It dates back to an early manuscript from the second century when the Greek letters T & P were superimposed over each other and used in the early Greek New...

This design is also called a staurogram or monogrammatic cross.  It dates back to an early manuscript from the second century when the Greek letters T & P were superimposed over each other and used in the early Greek New Testament...