Forgery, being the weirdest form of creativity there is, like antiques, costs lives. Why is it that antiques demand sacrificial victims? Dunno, but if they don't get enough, forgery does. You want proof? Here it is: Once a faker's found out, he dies. Truly. It always happens.
The sentiments attributed to Christ are in the Old Testament. They were familiar in the Jewish schools and to all the Pharisees, long before the time of Christ, as they were familiar in all the civilizations of the earth — Egyptian, Babylonian, and Persian, Greek, and Hindu.