Let's begin with a big one; chastity. Until the Hebrews got the law from God on Mt. Siani, there were no standing 'laws' governing sexual purity. The result from Moses' trips to the burning mountain top left the Hebrews with three basic principles: No sex outside of marriage, no sex with close relatives and no sex that is dangerous to the body. Other than that, God left the door wide open to the unusual imagination of the human mind.
Then Jesus came and took the law a step further. After all, didn't he come to fulfill the law, not condemn it? Jesus said that if a man looks on a woman with lust, he has committed adultery already, without having to physically do anything with her. As in all other forms, Jesus brought about a new ideal or standard involving sexual purity. He demanded that we not only keep our bodies clean, but also our hearts and minds.
This leaves us with the question 'Why'. What is so bad about sex outside of marriage, with close relatives and dangerous behavior? The last two (close relatives and physically dangerous sex) are obvious, but what is wrong with sex outside of marriage? There must be some reason God commanded this form of purity.
In the sixties, no one knew that promiscuity would lead to broken homes, emotional problems and rampant STD's. Now, after almost 40 years of experimentation and study, we are finally finding out the results of breaking this 4000-year-old commandment. Like most things, humans needed to find out why the laws existed before they would follow them. In the process, we screwed things up royally (no pun intended). You don't believe me? Read the 1596 articles dealing with premarital sex on the Focus on the Family webzine to back me up.
People who have sex before marriage are more likely to cheat on their spouses, seek a divorce and do a whole list of other unkind behaviors like spousal abuse. But as a thinker, I can't just assume a cause-and-effect connection. Somehow this must make sense. If God said is should not be done, then there must be a logical connection between the cause (sex) and the effect (social ills mentioned above). I think this connection lies in the standard people use for 'correct sexual expression'.
Imagine a man has sex with a woman because he feels a 'strong emotional connection' with her. He doesn't marry her because of some circumstance (money, time, current situation) but knows he will because of his deep love for her. After they get married, what happens if he feels a 'strong emotional connection' with his secretary? Since his standard for 'correct sexual expression' was based on emotion, he sets himself up for failure.
On the other hand, let's imagine a man who waits to get married, using that ceremony and vow as his standard for 'correct sexual expression'. Then if he develops a 'strong emotional connection' with another woman, he is less likely to jump into bed because his standard is measurable and concrete.
Not to be sexist, let us imagine the woman's side of things. A woman has sex with a man because he showed a genuine interest in her as a person. This guy was truly a gentleman and loved her dearly. They get married but then he drifts off into his job or hobbies (a very common occurrence) and she meets another man. This one also shows a genuine interest in her as a person, and since that was her standard for 'correct sexual expression' she goes ahead.
If your standard for sexual purity is anything less concrete than marriage, you are walking a dangerous line. Humans will always try to reason until they get their way. We are very good at finding excuses for bad behavior to gratify our Id (base desires). Without a concrete standard, it is too easy to convince yourself that what you are doing is right. If, however, your standard is marriage, it is fairly obvious that sex with your secretary is wrong (unless she's your wife).
However, infidelity is not the only result of premarital sex. A man and a woman get married because they have had sex and experience the usual flood of emotions connected to the act and the hormones it creates. In their 'rose colored world' they love each other through sex, and see sex as the glue that binds them, since they were, in all truth, combined into one flesh by that act. After time, the sexual drive wanes, as it always will, and the partners feel something is missing in their lives. They suddenly realize that sex was all they had in common and quickly divorce, ripping apart a family and two once-connected people.
I won't spend time here discussing the horror of divorce and the terrible, long-reaching consequences it harbors, but I will say here that infidelity is nothing compared to it. Of course, infidelity is the third most common reason for divorce, so they are closely related anyway.
Suspicion and distrust between spouses are another result of premarital sex. If your husband was willing to have sex with you before you got married, what is to prevent him from doing so again? And husbands, what's to prevent your wife from cheating on you since she was willing to go to bed with you without a wedding ring. If your spouse made you wait until you married him/her, you know they have a strong will, capable of withstanding the strong temptations that follow in the years after the ceremony. This distrust can also increase your chances for the aforementioned divorce.
Premarital sex can also cause unexpected and unwanted pregnancies. Many, today, simply opt for an abortion, but for those who want a pure decision, following through with the pregnancy is the way to go. Children raised in a 'forced home' do much more poorly in school, have trouble with emotional maturity, and are prone to divorce, delinquency and other problems.
Lastly, men and women truly want someone who is pure to marry. This was more obvious in the days previous to this sinful generation, but in many polls taken of high school and college students, an overwhelming majority preferred a spouse that waited until marriage. Do you remember the question 'why do guys want girlfriends willing to have sex, but virgin wives'?
The fact is marriage and raising children is extremely difficult. It is so difficult that no one goes through a married life without fights. I am talking about tough, hard fights that make you want to give up. But with true love and commitment, it is possible, and wonderful, if you go on through those problems to a brighter glory (what doesn't kill us makes us stronger). However, commitment is weakened when a couple engages in premarital sex, and so is the strength of the marriage. In today's world, I wouldn't bet on a marriage weakened in any way surviving.
If you are still unsure about the dangers of premarital sex, ask around. Even the liberal press and biased mass media claim that abstinence is the best way to go. They don't hide the facts, they simply try to downplay them. Do not be fooled! God said that sex before marriage (and outside of marriage) is a sin. He did so to protect us from the very problems mentioned above, and perhaps from some we haven't thought of yet.
If you are still tempted to do 'other things' that are not really sex, remember that Jesus said looking on a woman with lust is sexual impurity (I'm assuming the same goes for the girls). If this is true, it is very difficult to do these 'other things' without lusting in your heart for the woman.
Are you mad? Do you think I am wrong? Why? What is your reasoning behind your belief? I believe the bible, and it flatly says the sex outside of marriage is wrong. It goes on to say the lust outside of marriage is wrong. Therefore, if you do not believe the bible, listen to why God made that rule, and believe. I do not claim to know everything. I only claim that God had reasons behind every rule. I think it is now obvious why he made this one.