The Second London Baptist Confession of Faith (1689)

1. 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.¹

2. Marriage was ordained for the mutual help of husband and wife,² for the increase of mankind with a legitimate issue,³ and the preventing of uncleanness.⁴

3. It is lawful for all sorts of people to marry, who are able with judgment to give their consent;⁵ yet it is the duty of Christians to marry in the Lord;⁶ and therefore such as profess the true religion, should not marry with infidels, or idolaters; neither should such as are godly, be unequally yoked, by marrying with such as are wicked in their life, or maintain damnable heresy.⁷

4. Marriage ought not to be within the degrees of consanguinity or affinity, forbidden in the Word;⁸ 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.⁹