Is sex outside marriage a sin?

The apostle Paul listed sins of those who will not inherit the kingdom of God. The sins of adultery and fornication were right at the top of the list: 

“Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God.” 1 Cor 6:9-10. So adultery and fornication are definitely sins.   Sometimes saved people will slip into these sins. That does not mean that they lose their salvation.

A saved person is securely held by the power of God. They cannot become lost. What this is saying is that willful, practicing adulterers and fornicators will not go into God’s heavenly kingdom.   Just in case anybody needs more evidence that adultery and fornication are sins the book of Hebrews says “Marriage is to be held in honor among all, and the marriage bed is to be undefiled; for fornicators and adulterers God will judge.” Hebrews 13:4.   About right here is the point in this discussion where a lot of people usually start trying to build a logical argument as to why it’s ok. Common arguments are that nobody gets hurt or that that is not what the Bible really means.  

The fact is that people do get hurt by adultery and fornication. Besides the obvious STD threat there are the lives destroyed by cheating, the broken families, the lost trust, the feeling of being used and the compulsive behaviors of sexual addiction when people are wholly driven by sexual desire.   When people fornicate they are just using and abusing each other.

Oh, there may be some infatuation, but if there is no marriage committment it all just boils down to selfish use. To put it in modern terms looking at someone to lust after them or actually having casual sex with them is ‘objectifying’ them. It is to treat them as an object instead of a whole person.

They become just an object to be used for your personal sexual gratification.   I

If you are an unmarried woman in a sexual relationship, let me tell ask you this: Why would you let him have the benefits of marriage without the obligtions? Don’t you think that you are worth it? Why would you “sell yourself” (porneia) at such a bargain price?   Lastly, a life of sleeping around wears down the body because of the constant biological exposure: “you sleep with everyone your partners have slept with.” It’s unhealthy and debilitating over time.  

Let’s not water down the Bible on this topic. It is clear in what it says. Arguments to make it say something else are pointless. “Whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.” That’s the Lord Jesus’ clear standard. If even looking is a sin, then the doing most certainly is.

There’s no getting around it. If you don’t like what the Bible says on this subject, then as a free will creature you have the ability to rebell, but don’t try to make the Bible say something else.  

Source: http://www.landmark-lakewood.org/adultery.htm