Marriage should be honored by all, and the marriage bed kept pure, for God will judge the adulterer and all the sexually immoral. Hebrews 13: 4

Married couples are to honor the purity of their relationship by not having sexual relations with anyone outside of the marriage. To do so is to be an adulterer. Outsiders are to honor the marriage covenant by not engaging in sex with a married person. To do so is to be sexually immoral. Sexual immorality is defined by 1 Corinthians 7: 2— “But because of the temptation to sexual immorality, each man should have his own wife and each woman her own husband.”

Christians understand, then, that God has ordained sex to only be enjoyed between a husband (man) and wife (woman). What isn’t so commonly understood, though, is what sexual acts are deemed permissible or appropriate within the confine of marriage? The Bible doesn’t give us specifics, but, as is almost always the case, it does provide a guiding principle.

The principle is found in 1 Corinthians 7: 5— “Do not deprive each other except by mutual consent…” The key understanding here is that there should be agreement between the spouses. If one of the two is against trying something different, that person should not be forced to do it.

This doesn’t mean, though, that mutual consent trumps what we know to be outside of God’s boundaries for sex: adultery (including swapping or adding to the mix, in terms of threesomes or more) and bestiality.

Other than that, it appears that reliance on mutual agreement is biblically supported.