"For such are false apostles, deceitful workers, transforming themselves into apostles of Christ. And no wonder! For Satan himself transforms himself into an angel of light. Therefore it is no great thing if his ministers also transform themselves into ministers of righteousness, whose end will be according to their works." (2 Cor. 11:13-15)

A group of students at Harvard once tried to fool Agassiz, the famous professor of zoology. They took parts from a number of different bugs and with great skill attached them together to make a creature they were sure would baffle their teacher. On the chosen day they brought it to him and asked that he identify it. As he inspected it with great care, the students grew more and more sure they had tricked this genius. Finally, Professor Agassiz straightened up and said, "I have identified it." Scarcely able to control their amusement, they asked its name. Agassiz replied, "It is a humbug." (From Bible Illustrator)

A person who knows the truth will be able to detect a counterfeit when it presents itself.