"If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself." John 7:17
"If we want to have a living, abiding faith, we must be active in the performance of every duty as members of this church." (Teachings of Presidents of the Church: Joseph Fielding Smith. Chap. 5, pg 86.)
That's one remarkable thing about the gospel of Jesus Christ. If you are sincerely and actively engaged in a cause or a belief that is wrong, you will eventually become disillusioned and lose interest. But when people with honest hearts are actively living the true gospel of Jesus Christ to the best of their knowledge, they never become disillusioned and fall away. Never.