23 That day there came to him the Sadducees, who say there is no resurrection; and asked him, 24 Saying: Master, Moses said: If a man die having no son, his brother shall marry his wife and raise up issue to his brother. 25 Now there were with us seven brethren: and the first having married a wife, died; and not having issue, left his wife to his brother. 26 In like manner the second and the third and so on, to the seventh. 27 And last of all the woman died also. 28 At the resurrection therefore, whose wife of the seven shall she be? For they all had her. 29 And Jesus answering, said to them: You err, not knowing the Scriptures nor the power of God. 30 For in the resurrection they shall neither marry nor be married, but shall be as the angels of God in heaven.
The Sadducees asked Jesus, “if a man was married to more than one person in his life, to whom is he bonded with for eternity?”
Now, it seems as if Jesus replies that there is no eternal unity of the married in heaven. But then, what exactly is the sacrament of marriage?
Contrary to what some other religions believe, Catholics believe that when someone dies the marriage is over. As far as what happens in heaven when everybody is with God you will just have to wait and see.
As far as what is the Sacrament of Marriage -
Well, for a long time it wasn’t a Sacrament, but it has been for a while.
Sacraments are Holy. It is with and through the Sacraments that God encourages us to be Holy. It you are in a Sacramental marriage it will help you to be Holy, to be closer to God.
It is easy to think that Sacraments are magical, mysterious things only given to a few. This is very much not true. God wants to give His love, and the Sacraments, to all. If we do our part, and love God above all else, God will be with us.
So, to be practical, in a Sacramental marriage you will do things with your spouse and she/he will do things with you. You will want to be together all the time. All problems will seem small and your love will seem large. You will care about your spouse more than you care about yourself. Happiness will be your state.
Our ultimate destiny is to be married to God for all eternity. The Church is the “spotless bride” of Christ; heaven is the setting of the “marriage supper of the Lamb” that we read about in the Book of Revelation.
Think of marriage as a temporal “practice session” for the eternal “real thing.” We learn to selflessly love the God we cannot see by trying our best to love our spouse whom we can see. In doing so, hopefully the spouses lead each other to holiness and eternal life with God.
In the sacrament of marriage, one man and one woman give themselves completely to each other in love, and their love is fruitful in bearing children. In this way marriage is an image of the Trinity — the Father and the Son love each other, and their love is a Person — the Holy Spirit.
We will still love our spouses in heaven, but the exclusivity of that union will end, since we will be in perfect union with God.
You have to remember that while in the flesh your bodily actions are not only bodily, but that still our body belong to God. So the act of marriage is one of joining together to have a bonding of three people, male, female and the bonding is God. To enjoy unity and bring the next generation under God’s banner.
With this in mind the bonding of body of man and woman in the spirit is one of being with (if we are faithful to God) God for ever. In Heaven there is only rejoicing and blessing God, helping others ( without sin in the way) in the truest way possible. The man and the woman will both belong to God, no other.
Also, the purpose of marriage as described in the Catechism:
1659 St. Paul said: “Husbands, love your wives, as Christ loved the Church. . . . This is a great mystery, and I mean in reference to Christ and the Church” (Eph 5:25, 32).
1660 The marriage covenant, by which a man and a woman form with each other an intimate communion of life and love, has been founded and endowed with its own special laws by the Creator. By its very nature it is ordered to the good of the couple, as well as to the generation and education of children. Christ the Lord raised marriage between the baptized to the dignity of a sacrament (cf. CIC, can. 1055 § 1; cf. GS 48 § 1).
1661 The sacrament of Matrimony signifies the union of Christ and the Church. It gives spouses the grace to love each other with the love with which Christ has loved his Church; the grace of the sacrament thus perfects the human love of the spouses, strengthens their indissoluble unity, and sanctifies them on the way to eternal life (cf. Council of Trent: DS 1799).
1662 Marriage is based on the consent of the contracting parties, that is, on their will to give themselves, each to the other, mutually and definitively, in order to live a covenant of faithful and fruitful love.
1663 Since marriage establishes the couple in a public state of life in the Church, it is fitting that its celebration be public, in the framework of a liturgical celebration, before the priest (or a witness authorized by the Church), the witnesses, and the assembly of the faithful.
1664 Unity, indissolubility, and openness to fertility are essential to marriage. Polygamy is incompatible with the unity of marriage; divorce separates what God has joined together; the refusal of fertility turns married life away from its “supreme gift,” the child (GS 50 § 1).
1665 The remarriage of persons divorced from a living, lawful spouse contravenes the plan and law of God as taught by Christ. They are not separated from the Church, but they cannot receive Eucharistic communion. They will lead Christian lives especially by educating their children in the faith.
1666 The Christian home is the place where children receive the first proclamation of the faith. For this reason the family home is rightly called “the domestic church,” a community of grace and prayer, a school of human virtues and of Christian charity.
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1533 Baptism, Confirmation, and Eucharist are sacraments of Christian initiation. They ground the common vocation of all Christ’s disciples, a vocation to holiness and to the mission of evangelizing the world. They confer the graces needed for the life according to the Spirit during this life as pilgrims on the march towards the homeland.
1534 Two other sacraments, Holy Orders and Matrimony, are directed towards the salvation of others; if they contribute as well to personal salvation, it is through service to others that they do so. They confer a particular mission in the Church and serve to build up the People of God.
1535 Through these sacraments those already consecrated by Baptism and Confirmation1 for the common priesthood of all the faithful can receive particular consecrations. Those who receive the sacrament of Holy Orders are consecrated in Christ’s name "to feed the Church by the word and grace of God."2 On their part, "Christian spouses are fortified and, as it were, consecrated for the duties and dignity of their state by a special sacrament."3
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The grace of the sacrament of Matrimony
1641 "By reason of their state in life and of their order, [Christian spouses] have their own special gifts in the People of God."147 This grace proper to the sacrament of Matrimony is intended to perfect the couple’s love and to strengthen their indissoluble unity. By this grace they "help one another to attain holiness in their married life and in welcoming and educating their children."148
1642 Christ is the source of this grace. "Just as of old God encountered his people with a covenant of love and fidelity, so our Savior, the spouse of the Church, now encounters Christian spouses through the sacrament of Matrimony."149 Christ dwells with them, gives them the strength to take up their crosses and so follow him, to rise again after they have fallen, to forgive one another, to bear one another’s burdens, to "be subject to one another out of reverence for Christ,"150 and to love one another with supernatural, tender, and fruitful love. In the joys of their love and family life he gives them here on earth a foretaste of the wedding feast of the Lamb:
How can I ever express the happiness of a marriage joined by the Church, strengthened by an offering, sealed by a blessing, announced by angels, and ratified by the Father? . . . How wonderful the bond between two believers, now one in hope, one in desire, one in discipline, one in the same service! They are both children of one Father and servants of the same Master, undivided in spirit and flesh, truly two in one flesh. Where the flesh is one, one also is the spirit.151
You can go to scborromeo.org/ccc/index/a.htm and search alphabetically for lots of topics (including marriage – there’s a lot more than what I quoted above).