“Let marriage be held in honor among all, and let the marriage bed be undefiled, for God will judge the sexually immoral and adulterous” (Hebrews 13:4 AMP).
The creation account from the Biblical book of Genesis expresses God’s intent for marriage relationships by establishing a “one man – one woman” benchmark (see Genesis 2:22). That portion of Scripture thus confirms monogamy as God’s standard and eliminates the possibility of pre-marital, extra-marital, polygamous, or polyamorous physical relationships as legitimate options for a man or woman of God.
Nevertheless, some may validate their decision to engage in those relationships with an appeal to their belief that such partnerships “feel right.” However, “feelings” are a notoriously poor foundation for good decision-making, and it is possible to feel right about something that is far outside the will of God.
In addition to what we read here in Hebrews 13:4, the Scriptures offer several admonitions regarding these types of relationships (see Leviticus 18:20, Romans 1:26-27, 1 Corinthians 6:9, Ephesians 5:3, 1 Thessalonians 4:3-5, and Revelation 21:8 for some examples). While these alternative relationships fall short of God’s design for marriage, there is another reason to avoid engaging in such behaviors: “Sexual activity in a marriage is pure, but any sexual activity outside marriage brings one under divine judgment” (1)
Therefore, we would be wise to subject our feelings to these Biblical tenets instead of the other way around. This leads us into a look at the word “immoral” from this passage. That word is a form of the word porneia in the original language of this verse and refers to any type of sexual relationship that takes place outside a Biblically sanctioned marriage partnership. Jesus expanded upon that definition to include internal expressions of sexual immorality as well…
“You have heard that it was said to those of old, ‘You shall not commit adultery.’ But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart” (Matthew 5:27-28).
Therefore, the physical aspect of a male/female relationship is reserved exclusively for a man and a woman who have each made a permanent commitment to one other. That commitment is expressed by the act of marriage, where each marital partner publicly vows to forsake all others in favor of one. Since “Marriage is honorable among all” (GNV), it is important to support and encourage this institution, even among those who do not recognize or accept the God of the Scriptures.
(1) John F. MacArthur Jr., The MacArthur Study Bible: New American Standard Bible. (Nashville, TN: Thomas Nelson Publishers, 2006), Heb 13:4.