The Sixth Commandment

"You shall not commit adultery."  (Exodus 20:14)

After a thorough study of the scriptures, the Reformers summarized what the sixth commandment means in this way:  

"We should fear and love God so that we lead a sexually pure and decent life in what we say and do, and husband and wife love and honor each other."

God gives us our spouses (i.e., husband and wife) and knows who they will be from before we are born. He brings us together in His time and in His way. And He calls us to remain with the spouse that He gives us. (Jesus emphasized this in Matthew 19:3-8.)

That this relationship between husband and wife is also a sexual relationship is clear from the creation account. (See Genesis 1:26-28.) And that human sexuality is intended for marriage alone is the consistent witness of scripture. (The sin-describing words variously translated as "fornication" are used to describe all other sexual relationships. God never affirms human sexuality in any other context than marriage in the Bible.)

Having said that: The question of getting married "in the church" or "at the courthouse" is a different question. We get married under the rule of the state out of respect for the human authorities that God has put over us (see Romans 13), not because one requires a state certificate to be married.

However, for purposes of this commandment: Whether you are married "before the state" or not, you are married and had best start acting that way! To everyone out there living together "before marriage": Don't think you can "get out of it" more easily just because you aren't registered with the state! If you ask me, I counsel couples to "get married" before the state and before the church, but until you do: start thinking of yourself as married right now... because you are! If you aren't, you have no business in a sexual relationship!