Other than the church condemning me for living with my girlfriend, is there a real 
Bible prohibition against it? We are going to be married anyway, so what’s the problem?
Thank you for your openness, and your apparent honesty. Let me start with a story.
A man was notified that he would inherit $200,000 and the money would be in his bank account in six months. However, the man wanted to build a house immediately which would cost $150,000. Since he needed the money now and the money would be his anyway, he wrote a hot check to the builder for the full amount. He was going to get the money eventually, so what’s the problem?
It’s called breaking the law. He attempted to take the money before it was legally his, and he was arrested for it.
Back to marriage. That’s the problem here: experiencing the husband-wife intimacy prior to marriage is taking what is not rightfully yours. When men and women (at any age) indulge in sexual activity outside of marriage, they are stealing what is not theirs. It is breaking the law – GOD’s LAW.
It is also gambling on the shaky future. Supposing the expected marriage doesn’t take place? Thousands of times a year we hear the cry, “We were going to be married; but after all I gave him, he left me.”
Once that boundary (of illicit sexual activity) has been crossed, it is rarely re-established. We have often heard people complain, “But he promised that after we were married he would remain faithful to only me.” However, even if they remain physically true to each other, the underlying doubts of continued fidelity often evolve into open suspicion and conflict. “He did this with me outside marriage, I wonder if he will do this with someone else outside OUR marriage.” And often the infidelity continues.
Those who experience the intense joys of the physical union with someone other than their spouse rarely develop true loyalty or a deep-seated relationship with their spouse. Why? There is often a comparison taking place. Therefore, it is difficult to establish loyalty, faithfulness, love, devotion, and trust after you are married.
This is not only a “church” issue: it’s a physical, psychologica,l and mental issue. And yes, it is definitely a spiritual and Biblical issue.
Starting with Exodus 20:14 and ending with Revelation 2:22, adultery is mentioned 45 times, fornication 44 times, whoremonger 5 times, and the Bible gives a strong admonition against it.
In the Old Testament, the adulterer was to be put to death. In the New Testament, Jesus didn’t merely condemn the adulterer; He went further: Jesus reminded us that to even look on a woman with the wrong intent was equivalent to adultery. Hebrews 13:4 says, “Marriage should be honored by everyone, and husband and wife should keep their marriage pure. God will judge as guilty those who take part in sexual sins of any kind – heterosexual, homosexual, pornographic, child molestation, and all the rest.”
The issue goes deeper than lust or co-habiting out of wedlock. It is rooted in the comparison between marriage of man and woman, and mankind worshiping God. God created marriage (Genesis 2:18-25) to be holy, special, one man to one woman. Marriage was to be a human reflection of the relationship between humanity and God, and anyone or anything that corrupts this picture is an abomination or repugnance to God. That’s why the Bible equates adultery with idolatry and pagan worship (Jeremiah 3:8-9).
Remember the nagging question that will linger in the back of the mind: “Nothing prevented him/her from having sex with me before marriage; what will prevent him from doing this with someone else after we get married?” Committing adultery, fornication or whoredom creates a fault in the relationship that is almost impossible to repair.
To honor God and protect each other, wait until you’re married.
One last comment: if you have broken God’s law in this area, God will forgive you if you truly repent, and turn from this sin. God is a gracious and loving Father Who wants you
to have a wholesome, happy life. If you truly ask for forgiveness and marry your girlfriend, God can help you to have a strong marriage. But it will take extra effort, extra precaution, a purposed devotion and care for each other to verify your faithfulness.
Don’t live life YOUR way. Do it GOD’S way. You’ll be glad you did.
Carol and I were married on my 20th birthday: August 22, 1966. Carol says, “Marriage is made in Heaven; but it comes in a kit, and you have to put it together here on earth.” She is correct, and with God’s help we did a lot of “putting together” in our marriage. 
that sometimes.) And I learned that Carol was not being a demeaning tyrant who held me over the fires of hell every time I made a mistake. She was merely interested in truth: TOTAL truth. 
Gene Linzey 