Moroni 7

Mormon taught -

"Wherefore, all things which are good cometh of God; and that which is evil cometh of the devil; for the devil is an enemy unto God, and fighteth against him continually, and inviteth and enticeth to sin, and to do that which is evil continually.
13 But behold, that which is of God inviteth and enticeth to do good continually; wherefore, every thing which inviteth and enticeth to do good, and to love God, and to serve him, is inspired of God."  (Book of Mormon | Moroni 7:12 - 13)

Then Mormon provides this warning -

"...take heed, my beloved brethren, that ye do not judge that which is evil to be of God, or that which is good and of God to be of the devil."  (Book of Mormon | Moroni 7:14)

How do you judge?

"wherefore, I show unto you the way to judge; for every thing which inviteth to do good, and to persuade to believe in Christ, is sent forth by the power and gift of Christ; wherefore ye may know with a perfect knowledge it is of God.
17 But whatsoever thing persuadeth men to do evil, and believe not in Christ, and deny him, and serve not God, then ye may know with a perfect knowledge it is of the devil; for after this manner doth the devil work, for he persuadeth no man to do good, no, not one; neither do his angels; neither do they who subject themselves unto him."   (Book of Mormon | Moroni 7:16 - 17)

Very simple and direct.