“Sealed with That Holy Spirit of Promise”
12 That we should be to the praise of his glory, who first trusted in Christ.
13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise . . .
Elder Bruce R. McConkie wrote:
“The Holy Spirit of Promise is the Holy Spirit promised the Saints, or in other words the Holy Ghost. This name-title is used in connection with the sealing and ratifying power of the Holy Ghost, that is, the power given Him to ratify and approve the righteous acts of men so that those acts will be binding on earth and in heaven. ‘All covenants, contracts, bonds, obligations, oaths, vows, performances, connections, associations, or expectations,’ must be sealed by the Holy Spirit of Promise, if they are to have ‘efficacy, virtue, or force in and after the resurrection from the dead; for all contracts that are not made unto this end have an end when men are dead’ [D&C 132:7].
“To seal is to ratify, to justify, or to approve. Thus an act which is sealed by the Holy Spirit of Promise is one which is ratified by the Holy Ghost; it is one which is approved by the Lord; and the person who has taken the obligation upon himself is justified by the Spirit in the thing he has done. The ratifying seal of approval is put upon an act only if those entering the contract are worthy as a result of personal righteousness to receive the divine approbation. They ‘are sealed by the Holy Spirit of promise, which the Father sheds forth upon all those who are just and true’ [D&C 76:53]. If they are not just and true and worthy the ratifying seal is withheld. . . .
“Even if a person progresses to that state of near-perfection in which his calling and election is made sure, in which he is ‘sealed up unto eternal life’ [D&C 131:5; 132:18–26], in which he receives ‘the promise . . . of eternal life’ [D&C 88:3–4], in which he is ‘sealed up unto the day of redemption’ [D&C 124:124; Ephesians 1:13]—yet with it all, these great promises are secured only if the ‘performances’ are sealed by the Holy Spirit of Promise [Mormon Doctrine, 2nd ed. (1966), 361–62].”
(Doctrinal New Testament Commentary, 3 vols. [1965–73], 2:493–94.)