What is Marriage?
Marriage was ordained for the mutual help of husband and wife, for the increase of the human race with legitimate children, and for preventing immorality.
It is lawful for all sorts of people to marry who are able to give their rational consent, yet it is the duty of Christians to marry only in the Lord. Therefore those who profess the true faith should not marry unbelievers or idolaters. Nor should the godly be unequally yoked by marrying those who lead evil lives, or who maintain heresy.
Marriage must not to be contracted within the degrees of blood relationship or kinship forbidden in the Word, nor can such incestuous marriages ever be made lawful by any human law or consent of parties so that such people may live together as man and wife.
[The following two paragraphs are in the Westminster Confession, but not in the Baptist Confession]
When adultery or fornication committed after an engagement contract is detected before marriage, there are just grounds for the innocent party to dissolve the contract. In the case of adultery after marriage, it is lawful for the innocent party to sue for a divorce, and after the divorce to marry another—it is as if the offending party were dead.
Human corruption is such that clever arguments will be brought to separate those whom God has joined together in marriage. Yet nothing but adultery, or wilful desertion that cannot be healed by the church or civil authority, is sufficient cause for dissolving the bond of marriage. Such dissolution is to be conducted in public and an orderly course of proceedings is to be observed; the persons concerned in it should not be left to their own wills and discretion.