Westminster Confession of Faith

Marriage is to be between one man and one woman: neither is it lawful for any man to have more than one wife, nor for any woman to have more than one husband; at the same time.⁴⁷⁵

Marriage was ordained for the mutual help of husband and wife,⁴⁷⁶ for the increase of mankind with a legitimate issue, and of the Church with an holy seed;⁴⁷⁷ and for preventing of uncleanness.⁴⁷⁸

It is lawful for all sorts of people to marry, who are able with judgment to give their consent.⁴⁷⁹ Yet is it the duty of Christians to marry only in the Lord:⁴⁸⁰ and therefore such as profess the true reformed religion should not marry with infidels, papists, or other idolaters: neither should such as are godly be unequally yoked, by marrying with such as are notoriously wicked in their life, or maintain damnable heresies.⁴⁸¹

Marriage ought not to be within the degrees of consanguinity or affinity forbidden by the Word;⁴⁸² nor can such incestuous marriages ever be made lawful by any law of man or consent of parties, so as those persons may live together as man and wife.⁴⁸³ The man may not marry any of his wife's kindred nearer in blood than he may of his own; nor the woman of her husband's kindred nearer in blood than of her own.⁴⁸⁴

Adultery or fornication committed after a contract, being detected before marriage, giveth just occasion to the innocent party to dissolve that contract.⁴⁸⁵ In the case of adultery after marriage, it is lawful for the innocent party to sue out a divorce:⁴⁸⁶ and, after the divorce, to marry another, as if the offending party were dead.⁴⁸⁷

Although the corruption of man be such as is apt to study arguments unduly to put asunder those whom God hath joined together in marriage: yet nothing but adultery, or such wilful desertion as can no way be remedied by the Church or civil magistrate, is cause sufficient of dissolving the bond of marriage:⁴⁸⁸ wherein, a public and orderly course of proceeding is to be observed; and the persons concerned in it not left to their own wills and discretion, in their own case.⁴⁸⁹