For this reason a man will leave his father and mother and be united to his wife, and they will become one flesh.
-Genesis 2:24
Do you not know that he who unites himself with a prostitute is one with her in body? For it is said, “The two will become one flesh.”
-1st Corinthians 6:16
The truth is that wherever a man lies with a woman, there, whether they like it or not, a transcendental relation is set up between them which must be eternally enjoyed or eternally endured.
-CS Lewis, The Screwtape Letters
Sexual intercourse is an act of the whole self which affects the whole self; it is a personal encounter between man and woman in which each does something to the other, for good or for ill, which can never be obliterated. This remains true even when they are ignorant of the radical character of their act.
-Derrick Bailey, The Mystery of Love & Marriage.
According to the biblical authors, sexual intercourse creates a mysterious, unique “one flesh” bond.”
-Richard Foster, The Challenge of the Discipline Life
What does the Bible say about sex? You don’t have to read very far to find out. Just read through the second chapter of Genesis and you’ll see God’s plan: one man and one woman in a lifetime covenant of marriage.
One Flesh
But there’s more—a powerful poetic expression: “one flesh.” These two words describe the physical, emotional, and spiritual bond created by sexual intercourse. Like it or not, sex is a life-uniting act—the union of two souls.
“Safe sex,” therefore, is a fictitious idea. We may protect ourselves from the physical consequences of sex, but contraceptive devices do not protect one’s soul. The emotional/spiritual consequences of non-marital sex are simply unavoidable.
I’ll give you a simple illustration. Imagine two pieces of paper which have been glued together. Now, imagine trying to separate the two pieces. I’ve done this simple demonstration with hundreds of students. The result is always the same: complete separation is simply impossible. The bond formed by the glue irreversibly transforms the two pieces into one.
Something similar happens to us when we create permanent, one-flesh bonds within temporary (non-marital) relationships—we tear our soul to pieces.
Think about it.