Proverbs 16:28 - A froward man soweth strife: and a whisperer separateth chief friends.
Have you ever played the Whispering Game? That fun game where someone is given a message and each person down the line is to whisper it to the next person? Never in the history of me playing that game has the message ever been close to the original. Fun when it's a game, but momentously frustrating in real life.
Too many times satan uses others to pass the message of the Gospel incorrectly. We are told that we must earn salvation through good works, rather than through the blood of Christ. If that doesn't work, then he whispers untruths or half truths about what the Christian life is or is not. Pass it along enough with just a little alteration each time and the message ends with something the Lord never intended.
What's the lesson? No matter who is whispering in your ear, go back to the original source to know what is true.