First things first, Jesus doesn’t talk much about sex before marriage. If he did, you would begin to suspect that someone had doctored the text of the Bible because first-century Jews got married shortly after puberty (girls around 13 or 14, guys a little bit older). Consequently, sex before marriage simply wasn’t a major issue. In a sex-saturated culture like our own it’s hard to imagine 12 and 13-year-olds still acting like children and getting nervous rather than excited about their wedding night, but that’s how it was in the first-century Jewish culture which received Jesus’ firsthand teaching.
 
That said, adultery - sex outside of marriage - was definitely an issue. The flip side of parents marrying off their children young, often to relative strangers, was that not all first-century marriages were happy. They were as predisposed as we are to look for sex with other people’s husbands and wives, albeit without some of the easy outlets which exist in our own culture to turn desire into action. This means we have to apply the three golden rules of understanding Scripture to Jesus’ teaching on sex and ask firstly “What did Jesus say to his original hearers?”, then secondly “What is Jesus therefore saying to us today?”, and thirdly “How does Jesus want me to apply that teaching to my life?”
 
Perhaps the most obvious passage to start with is Jesus’ words in Matthew 19:1-12. Jesus is talking about marriage and divorce, so we need to study the passage carefully for our own context, but some of what he says is very relevant to the question of sex before marriage. Jesus asks his listeners in verses 4 to 6:

Haven’t you read that at the beginning the Creator ‘made them male and female,’ and said ‘for this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’? So they are no longer two, but one. Therefore what God has joined together, let man not separate.

 
Let’s take a moment to consider what Jesus is teaching us here.
 
1) Sex is good
Why is it that Christians seem louder at talking about how not to have than how to have sex?! It’s like the Monty Python sketch in the movie The Meaning of Life, where the Protestant male rejoices that he isn’t repressed like the Catholics whilst completely ignoring his wife’s come-to-bed-with-me eyes. Tony Campolo puts it even more starkly, claiming that “We were taught that sex is a dirty, filthy thing, and you should save it for the person you marry!”
 
Jesus, in contrast, points us back to Genesis 1-2, where the Lord creates human beings male and female, tells them to go forth and multiply and then declares that everything he has made (including sex) is “very good”. It’s passages like this one that led the author of Hebrews 13:4 to write that “the marriage bed should be kept pure” (not made pure) because sex within marriage is a wonderful gift from our Creator. If your understanding of Jesus’ teaching on sex gives you a low view of sex, then you have misunderstood him. Go and read the Old Testament book of Song of Songs if you need any encouragement to believe that God says sex is good!
 
2) Sex is better than good
Now get ready for something shocking. Jesus tells us that sex isn’t just good, it also reflects something of the divine nature of God. He expects us to go back to the passage he quotes from Genesis 1:26-27 and read the whole verse: “God said, ‘Let us make mankind in our image, in our image and let them rule’ ... So God created mankind in his own image, in the image of God he created him; male and female he created them.” Now read that again more slowly. It says God made human beings male and female in order that we might reflect his own image - “our own image”, as he puts it, referring to the three-in-one Trinity. For mankind, it’s only two-in-one because we are not God, but it is two-in-one for a reason. Sex isn’t merely recreational and consensual. It is an act of worship through which two human beings reflect the image of God - a God who is more than one person and yet One.
 
You’ve got to understand this as a central plank of Jesus’ argument if you want to understand what he says. It’s why the Mosaic Law commanded the death penalty for relatively few offences compared to the other law codes of its day, and yet included sexual sin among the handful of crimes which were punishable by death. Jesus intervened to save an adulteress from being stoned to death in John 8, but he didn’t play down the seriousness of her crime when he warned her to “Go and leave your life of sin.” The Old Testament treated sexual sin as a form a of blasphemy, a vile parody of the Trinity, and Jesus endorsed and reinforced that view. Although he didn’t talk much about sex before marriage because it wasn’t much of an issue in his culture, he tightened up the Law when it came to adultery, declaring that even lusting after a person we are not married to puts us in danger of hell fire.
 
3) Sex doesn’t belong to us
Consequently, Jesus teaches in Matthew 19 that sex does not belong to us. That’s pretty controversial in our culture, where anything goes sexually (and the painful consequences are everywhere), but it stands to reason when we grasp that Sex Is Good and that Sex is Better than Good. If God is our Creator and he made humans male and female in order to reflect his glory to the world, then it stands to reason that he can tell us sex belongs to him. We are like renters who have been allowed to live in an apartment which belongs to God, not to ourselves, and God takes it very seriously when we start knocking down the walls of the apartment as if it all belongs to us.
 
That’s the bottom line when it comes to following Jesus’ words on sex. It’s a question of whether we believe our lives (sexual or otherwise) belong to him or to ourselves. If we want to live for Jesus, then he tells us that sex is even better than we thought. Not only can we enjoy it far better in its proper, God-created context, but we are also reflecting the glory of the Trinity when we do! But it also means that Jesus wants to be Lord of what we do in our bedroom (etc, etc!) in private, because our whole lives belong to him.
 
4) Marriage is God’s invention not ours
Jesus hasn’t finished. He has one more big thing to say. He doesn’t just talk about two becoming one, but starts to talk about a person leaving his parents and being united to his wife (note the order), and he tells us that when such a public marriage covenant takes place then God has joined the two marriage partners together in a way which human laws alone cannot separate. The disciples don’t know whether to be horrified that marriage is such a serious matter (they ask if it might be too holy a state to enter into at all in verse 10), or to be overjoyed that God’s plan for sex and marriage is so much better than the way these things are viewed in their culture (we can tell from the New Testament letters that this second option ultimately won their hearts). Jesus tells us that we have only understood what he says about sex if we are similarly overawed and overjoyed.
 
Conclusion
 
We have only looked at four short verses from one portion of Jesus’ teaching on sex, but what can we conclude? Jesus is clear that sex is reserved for lifelong marriage between one man and one woman, and that he created it to be incredible fun so that we would make love often and enjoy it - whilst reflecting the fact that God is far greater than a man or a woman. They are two-in-one, shining like the moon, whilst he is three-in-one, shining far more brightly like the sun.
 
If you are not living this way, then sex should not be a reason for you to reject Jesus but for you to accept him. Our culture is full of good reasons for bad sex, but Jesus promises that if we follow the Maker’s instructions then sex gets better. He also promises you forgiveness as he did the adulterous woman in John 8, telling you “I do not condemn you; now leave your life of sin.” 
 
If you are not yet married but are trying to live Jesus’ way, then you should be encouraged. Jesus promises you that God greatly prizes your decision to remain celibate until you marry, and that he will bless you as a result. Perhaps he is already planning your reward. Proverbs 18:22 tells us that  “He who finds a wife finds what is good and receives favour from the Lord.”
 
And if you are married, then please don’t focus more on Jesus’ prohibitions on sex than you do on his great invitation. He encourages you to go and make love to your husband or wife to the glory of God! He tells you that some of your best worship should not be sung in church on a Sunday morning, but enjoyed in bed on a Sunday afternoon! In fact, shouldn’t you stop spending time reading this blog and go forth to apply it for the glory of the Triune God?!