In volume 4 of their A Commentary on the Doctrine and Covenants, Stephen E. Robinson and H. Dean Garrett provided the following exegesis of D&C 129 (footnotes have been renumbered), one of the more unique sections therein:
1. Two kinds of beings in heaven. It seems that Joseph Smith is using the term "beings" here to mean human beings, because there are a number of other beings near the throne of God.[1] Moreover, the term "heaven" seems to be used here broadly as equivalent to "the other side of the veil," because such translated beings as Enoch, John the Beloved, or the Three Nephites, who have not yet passed through the veil but might otherwise be considered angels (as, for example, in 3 Nephi 28:30), are not included here.
1. Angels, who are resurrected personages, having bodies of flesh and bones. The Hebrew word malak and the Greek word angelos, which are both translated as "angel" in the Bible, mean "a messenger." Because none of the angels described in scripture before the resurrection of Jesus Christ can possibly have been resurrected (1 Corinthians 15:20, 23), it is clear that Joseph is defining his terms here from a postresurrection perspective. Before the resurrection of Christ and in certain other contexts, the term "angel" has been used in the scriptures more generally for both spirits and translated beings (compare Psalm 104:4; D&C 76:25; 84:28; 130:5; Luke 1:19; 2:15; 1 Nephi 1:8; Moses 5:58). In this revelation, however, angels are clearly understood as those "who are resurrected." The important point here is that God might send as messengers either physical beings or spirits; in either case, it is important for us to know how to be sure that they are truly from God.
2. Jesus said. This statement is recorded in the New Testament in Luke 24:39.
3. The spirits of just men made perfect. See Commentary on Doctrine and Covenants 76:69. It is possible that God might send as a messenger someone who has passed through mortality and died, who is worthy of celestial glory through faith in Christ, but who has not yet been resurrected. This would be the spirit of a just man made perfect in Christ.
4–8. Offer him your hand and request him to shake hands. The same test is to be applied in all cases to messengers claiming to be from God, whether they are resurrected angels or disembodied spirits. There are three possible outcomes whenever this test is applied: (1) An angel from God who is a resurrected being will shake the offered hand, and you will feel the substance of his flesh and bones (Luke 24:39) and know that he is from God. (2) The spirit of a just man made perfect will not take the offered hand. Neither will he move to avoid your touch but will stand his ground and still deliver his message. In this way, you will know that he is the spirit of a just man made perfect and is from God. (3) The devil or a false spirit will attempt to masquerade as a resurrected being and shake hands, but you will not feel flesh and bones and can thus avoid being deceived.
6. He will come in his glory. Without a physical tabernacle of flesh and bones, such as a resurrected angel possesses, a perfected spirit cannot hide his glory from the one to whom he appears. It seems that hiding one's glory is a prerogative of resurrected beings (Luke 24:15–16, 31; John 20:14–15; 21:4).
7. He will not move. The version of these instructions from Joseph written in William Clayton's "Private Book" in December 1840 specified that a spirit from God would not move either to shake your hand or to shrink back to avoid being touched, whereas an evil spirit would move in either of these ways.[2]
8. The devil as an angel of light. See the Commentary on Doctrine and Covenants 128:20. Satan does have the power to deceive the unwary (2 Thessalonians 2:4). The Prophet taught: "It would seem also, that wicked spirits have their bounds, limits, and laws by which they are governed or controlled, and know their future destiny, hence, those that were in the maniac said to our Savior, 'Art thou come to torment us before the time,' and when Satan presented himself before the Lord, among the sons of God, he said that he came 'from going to and fro in the earth, and from wandering up and down in it'; and he is emphatically called the prince of the power of the air; and, it is very evident that they possess a power that none but those who have the Priesthood can control."[3]
9. Three grand keys. These are composed of the test proposed in verse 4, shaking hands, and the three possible outcomes that will occur, depending on whether the messenger is (1) a resurrected being from God, (2) the spirit of a just man made perfect, also from God, or (3) a deceiving spirit of the devil.
Notes for the Above
[1]. D&C 77:1–2; Revelation 4:6–9, 5:13; Smith, History of the Church, 5:324.
[2]. See Ehat and Cook, Words of Joseph Smith, 44; see also Woodford, "Historical Development," 2:1703.
[3]. Smith, History of the Church, 4:576.