No, it isn’t being sealed to your spouse on wedding day, although that is a prerequisite (preparatory and required) to receive this highest and most sacred sealing ordinance. The priesthood sealing powers of Elijah, as restored in this last dispensation (D&C 110:13-16) and vested in the presiding high priest of the Church (D&C 132:7), are truly infinite in their application, being enabled to promise eternal life and exaltation to the faithful saints while yet in this life, as Peter explained to the ancient saints (2 Pet. 1; Eph. 1:13-14). Those saints who so receive are they who are of the church of the Firstborn (D&C 76:54, 94), and who may then receive the Second Comforter (D&C 88:3-5).
The Prophet Joseph Smith declared:
After a person has faith in Christ, repents of his sins, and is baptized for the remission of his sins and receives the Holy Ghost, (by the laying on of hands), which is the first Comforter, then let him continue to humble himself before God, hungering and thirsting after righteousness, and living by every word of God, and the Lord will soon say unto him, Son, thou shalt be exalted.
When the Lord has thoroughly proved him, and finds that the man is determined to serve Him at all hazards, then the man will find his calling and his election made sure, then it will be his privilege to receive the other Comforter, which the Lord hath promised the Saints, as is recorded in the testimony of St. John, in the 14th chapter, from the 12th to the 27th verses. ((TPJS, 149-151.))
I would exhort you to go on and continue to call upon God until you make your calling and election sure for yourselves, by obtaining this more sure word of prophecy, and wait patiently for the promise until you obtain it. ((ibid., 299.))
Dr. Andrew C. Skinner, currently Executive Director of The Neal A. Maxwell Institute for Religious Scholarship at BYU, provides more insight into these sacred principles in his recently published book, Temple Worship:
Another aspect of the sealing power of the priesthood is the ability of the Lord’s authorized servant to seal men and women unto eternal life, to perform an ordinance granting them eternal life once they pass beyond mortality, “to place a seal on them so that no matter what happens in the world, no matter what desolation sweeps the earth, yet they shall be saved in the day of the Lord Jesus. (D&C 88:84-85; D&C 109:38, 46; D&C 124:124; D&C 131:5; D&C 132:19, 46, 49).” ((McConkie, Mormon Doctrine, 683.)) Elder Bruce R. McConkie added this significant insight: “Since these sealing blessings are conferred by the laying on of hands of those who hold the keys of this power, it follows that John’s description of placing a seal in the forehead is not just apocalyptic imagery but a literal description of what takes place. As with other sacred things, however, the devil has a substitute seal to place; he puts a mark in the ‘foreheads’ of his followers also. (Rev. 13:16-18)” ((ibid.)) ((Skinner, Temple Worship, 2007, 74; emphasis added.))
As Elder McConkie noted, this sealing is “conferred by the laying on of hands” and therefore is a different sealing than when one is first married and sealed in the temple. Being sealed to your spouse initially at the altar and its associated promised blessings (including those mentioned in D&C 132) are contingent upon enduring faithfulness and righteousness throughout one’s lifetime, whereupon one may then receive this final sealing and ordinance:
The sealing of men and women (couples) to eternal life is predicated upon continued faithfulness in mortality over time, after their temple marriage, and is not automatic or inherent in the marriage ceremony when a couple is first married in the temple, as temple instruction makes clear. Said President Joseph Fielding Smith, “Blessings pronounced upon couples in connection with celestial marriage are conditioned upon the subsequent faithfulness of the participating parties.” ((Smith, Doctrines of Salvation, 2:46.)) In fact, exaltation comes as a result of proven loyalty to the Lord and his kingdom “at all hazards.” ((Smith, TPJS, 150.)) The Prophet Joseph Smith not only described the kind of complete devotion to righteousness that is required to receive this ultimate blessing but showed us the way. ((ibid., 149-51.)) In 1843, after years of serving the Lord at all hazards, Joseph heard the Lord say: “For I am the Lord thy God, and will be with thee even unto the end of the world, and through all eternity; for verily I seal upon you your exaltation, and prepare a throne for you in the kingdom of my Father, with Abraham your father” (D&C 132:49). ((Skinner, Temple Worship, 2007, 74-75; emphasis added.))
We might ask, “Must we receive this ordinance in mortality, or can it be administered vicariously after we have passed on?” Dr. Skinner helps us in understanding:
Regarding the rest of us, the Lord indicates in D&C 50:5 that whether such a guarantee comes before death or after mortality has concluded, it makes no difference. The result is the same—exaltation. That is why it is so important for all of us to endure faithfully, patiently, and cheerfully to the end of our mortal lives.
In a way, the temple endowment is preparation for the sealing ordinance of eternal marriage, which in turn is preparation for the promise of eternal life preparatory to the realization of exaltation. ((Skinner, Temple Worship, 2007, 75; emphasis added.))
I would add that baptism and receiving the gift of the Holy Ghost (a type of washing and anointing) are also preparation for the temple ordinances which include initiatories (washing and anointing – D&C 124:39), which are in turn preparation for these higher sealing blessings. Undoubtedly these ordinances have a relationship to the three degrees of glory found within the celestial kingdom (D&C 131:1-5).
Note that this sealing ordinance clearly does not make one like God while in this life, but is the promise, save committing the unpardonable sin (D&C 132:26-27), that one will eventually receive such an inheritance in the hereafter (Rom. 8:16-17; Gal. 4:7). Joseph Smith taught us:
When you climb up a ladder, you must begin at the bottom, and ascend step by step, until you arrive at the top; and so it is with the principles of the Gospel-you must begin with the first, and go on until you learn all the principles of exaltation. But it will be a great while after you have passed through the veil before you will have learned them. It is not all to be comprehended in this world; it will be a great work to learn our salvation and exaltation even beyond the grave. ((TPJS, 348.))
More can be learned about this most solemn and sacred ordinance and it’s associated principles at the following links: