1 Nephi 17:44

In verse 44, Nephi transitions from talking about the spirituality of the Israelites and their decedents to the spirituality of his brothers. He compares them again to the Jews that sought to take away the life of their father. He says an interesting comment after that. Because they've obviously have not gone through with it, but have thought about it and seriously have wanted to do it, he's said that they are murderers in their hearts. Thus, they were just like the majority of the Jews in Jerusalem at that time. I thought that this was interesting because they were somewhat guilty of the sin for even just thinking about it, wanting to do it, and not doing it. Now, I think that if one is repentant they can be forgiven of bad thoughts and intentions, but we have commented on this before, with respect to Laman and Lemuel, and later on we will see their choice of whether or not to follow God.

Now, I'm not the judge and some might think Nephi seems harsh in his comment, but I am inclined to believe him and say that even our thoughts will condemn us and we must master not only our body in this mortal existence, but our minds, too. This idea comes from a few other places in the scriptures that talk more about it.

The first comes from Alma 12:14, which says:

"For our words will condemn us, yea, all our works will condemn us; we shall not be found spotless; and our thoughts will also condemn us; and in this awful state we shall not dare to look up to our God; and we would fain be glad if we could command the rocks and the mountains to fall upon us to hide us from his presence" (emphasis added).

The next scripture comes from Mosiah 4:30, which says:

"But this much I can tell you, that if ye do not watch yourselves, and your thoughts, and your words, and your deeds, and observe the commandments of God, and continue in the faith of what ye have heard concerning the coming of our Lord, even unto the end of your lives, ye must perish. And now, O man, remember, and perish not."

The final scriptures are about committing adultery in your heart. This is a lot like the phrasing that Nephi uses, but with regard to adultery rather than murder, which is the next worst sin to commit (see Alma 39:5). We begin with Jesus's commandment from the Sermon on the Mount (Matthew 5:28, 3 Nephi 12:28), which says:

"But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart."

The Doctrine and Covenants adds to this by saying:

"And he that looketh upon a woman to lust after her shall deny the faith, and shall not have the Spirit; and if he repents not he shall be cast out" (Doctrine and Covenants 42:23, 63:16).

Because this is true, I will guess that because no one can see our thoughts, then we are tempted to think what we please. President Boyd K. Packer of the Quorum of Twelve Apostles gave us a great suggestions to help control our thoughts in his talk Worthy Music, Worthy Thoughts.