275. Christ has laid down clear laws for those who enter on the matrimonial state. He says "From the beginning of the creation, God made them male and female. For this cause a man shall leave his father and mother, and shall cleave to his wife, and they shall be two in one flesh. Therefore now they are not two but one flesh. What therefore God hath joined together let not man put asunder. . . . Whosoever shall put away his wife and marry another, committeth adultery against her. And if the wife shall put away her husband, and be married to another, she committeth adultery" (Mark X, 6-12). From the teaching of Christ in this and other texts we see 1. That the natural marriage instituted in the creation (Gen. II, 21-24), consisted in the agreement between a man and a woman to enter into life-long cohabitation; the contract itself to take each other as man and wife constituted the marriage 2. That it excluded any third person from the partnership, and thus made polygamy unlawful 3. That no one could dissolve what God had thus united 4. That the two parties were bound by the contract to love each other and bear each others burden, so as to live, not as two, but as one person; 5. That divorce, which Moses allowed under peculiar circumstances (Deut. XXIV, 1), was a departure from the original design of Matrimony and had been allowed to the Jews, only on account of the hardness of their hearts; 6. That Christ abolished this relaxation of the law; for He says that, if a separation do take place, a second marriage during the life of both parties is adulterous, which it could not be if the former union had been dissolved. But He does not condemn repudiation of the guilty party "for the cause of fornication" (Matt. V, 32), yet without severance of the marriage bond. The only separation He allows is what is called "of bed and board"; 7. That the rights and duties of the married state are not derived from the civil power, since they existed before States were instituted, and are more deeply rooted in the nature and the wants of man than any civil allegiance. Therefore the State cannot legislate concerning the bond of matrimony, nor interfere with the duties essentially involved in it, for instance the education of the children. All it can do is to protect the natural rights of husband and wife, parents and children.
276. While Christ thus restored matrimony to its pristine purity, He also raised it to the supernatural dignity of a Sacrament. St. Augustine ranks it with Baptism and Holy Orders (De Nupt. Conc. I, c. 10). Tradition had taught this doctrine without any contradiction, before the Councils of Florence and of Trent (Sess. 14, can. 1) defined it to be of faith. St. Paul had said "This is a great Sacrament; but I speak in Christ and in the Church" (Eph. V, 32). It is not a Sacrament when contracted by the unbaptized; but between Christians marriage is always a Sacrament. Its essence lies, as is clear from time Council of Trent, in the contract freely made between man and wife; this contract itself, in the case of baptized persons, has been made by Christ productive of grace. The grace it confers is, first, an increase of sanctity, and secondly, actual grace to fulfil meritoriously the duties of the married state, especially those of love and fidelity between the married couple. and of proper care in the education of their children.
277. Since the contract itself is the Sacrament, the contracting parties are its ministers; their own persons are the matter affected, and the form consists in the signification, or expression, of their mutual consent. Christian Marriage has a special spiritual meaning: it represents the union of Christ with His Church; for St. Paul writes, "The husband is the head of the wife, as Christ is the head of the Church. . . . Therefore, as the Church is subject to Christ, so also let wives he subject to their husbands in all things. Husbands, love your wives, as Christ also loved the Church, and delivered Himself up for it" (Eph. V 22-29).
From the fact that Christian Matrimony is a Sacrament, it follows that it is entrusted to the care of the Church and subject to her laws, not to those of the State. As civil contracts rest upon the natural law established by the Creator, and yet are regulated by the laws of the land, which can even invalidate some of them; so the marriage contract between Christians rests on the Divine law, but yet is to be regulated by the legislation of the Church, which can also invalidate the contract in special circumstances (nn. 351).