What is the difference between an evil spirit and a false spirit? I was reading in 1 Kings 22 where it is said that the Lord sent a false spirit to the prophets. I didn't think that prophets could say things that weren't true. I also heard that sometimes we receive false spirits and think that that is an answer to prayer. I am a little confused.

The terms "evil spirit" and "false spirit" refer to the same class of being, as explained in D&C 129.

As to the scriptures in 1 Samuel 16:14 and 1 Kings 22:23, the prophet Joseph Smith's translation suggests that these passages were mistranslated or that there were other errors. The prophet corrected the one in 1 Samuel to say "But the Spirit of the Lord departed from Saul, and an evil spirit which was not of the Lord troubled him." (JST 1 Samuel 16:14) And even though no correction was made to the passage in 1 Kings, the same passage is also found in 2 Chronicles, and there the prophet corrected it in this manner: "Now therefore, behold, the Lord hath found a lying spirit in the mouth of these thy prophets, and the Lord hath spoken evil against thee." (JST 2 Chronicles 18:22)

As to false spirits in our midst, these following scriptures should help you understand how to identify false spirits, false doctrines, and their followers:

"Behold, verily I say unto you, that there are many spirits which are false spirits, which have gone forth in the earth, deceiving the world."  (D&C 50:2)

"Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world. Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God ... "  (1 John 4:1-3)

"And again, I will give unto you a pattern in all things, that ye may not be deceived; for Satan is abroad in the land, and he goeth forth deceiving the nations--Wherefore he that prayeth, whose spirit is contrite, the same is accepted of me if he obey mine ordinances. He that speaketh, whose spirit is contrite, whose language is meek and edifieth, the same is of God if he obey mine ordinances. And again, he that trembleth under my power shall be made strong, and shall bring forth fruits of praise and wisdom, according to the revelations and truths which I have given you. And again, he that is overcome and bringeth not forth fruits, even according to this pattern, is not of me. Wherefore, by this pattern ye shall know the spirits in all cases under the whole heavens."  (D&C 52:14-19)

I hope this helps. If not, ask me and I'll send more information.