What is the Purpose of Sex?

Does sex have a purpose, or purposes, or, as the evolutionists would have us believe, is it merely a quirk of evolution, a phenomenon which occurred through random mutation and turned out to give a survival advantage to the flora and fauna in which it developed?

The Bible says nothing about evolution, but it does tell us that sex was designed and implemented by God when He created living beings on the earth, specifically human beings. It also tells us that He had two distinct but related purposes in mind when He did so. The first of these is found in the first chapter of the first book of the Bible, and has been partially quoted already. Here it is in full:

When God made mankind, He made us MALE and FEMALE, and then told us to “be fruitful and increase in number”. So, very clearly, God’s initial purpose for sex is REPRODUCTION.

This should come as no surprise to anyone, since we all know that babies are not brought by storks and found under gooseberry bushes or in cabbage patches. (Apologies to anyone who finds my candour offensive!)

The second purpose for sex is found in the second chapter of Genesis:

This second chapter homes in on the personal and intimate relationship that God entered into with the man that He made in His image, and we see here that the man is not just a well-developed simian, but from the very beginning is possessed of intelligence and perspicacity, with the ability to see an animal, perceive its nature, and assign an appropriate name to it. John Lennox makes the point that this is the first example of the scientific discipline of taxonomy.

But for all of Adam’s strengths and capabilities, he has one glaring weakness – he is alone, and that is, in God’s own words, not good. He is in need of a helper who is just right for him, tailor-made for the purpose.

Before we go on, I think we need to address a concern that some readers may have, that this creation account puts women in a place of inferiority to men, since God seems to be wanting for Adam not a partner but a helper, a ‘Girl Friday’ to his Robinson Crusoe.

To answer this, let’s look at another scripture where this same word, translated as ‘helper’, is used:

This is but one of a number of scriptures where the same Hebrew word (pronounced ‘AY-zer’) is used of God Himself being a man’s helper.

So, ladies, take heart: God considers you to have a very special place in the life of your man. Just because men don’t realise it doesn’t mean that it’s not true!

Now, we need to pay attention to who it is that God appointed to be Adam’s helper. A dog may be man’s best friend, but is no good when a man needs a helper.

Similarly, God did not choose another man, because what Adam needed was not someone to stand with him shoulder to shoulder, or head to head, but someone who would stand with him heart to heart. Remember, it was from a rib that God formed the woman, so that her inclination would be to return to where she came from, as it were, and to cover her man’s heart.

The other essential point about God’s choice was that if Adam were to be the father of any children, then those children could only be born if they had a mother. For this reason, Adam chooses to call his wife ‘Eve’, which is a Hebrew word meaning ‘life-giver’:

Given, then, that the primary purpose of sex is to produce life, let’s have a look again at verses 23 and 24 of chapter 2. Here they are in the old King James version:

Adam and Eve are, of course, unique in that they were the first man and woman, and Adam could say, quite literally, that Eve was ‘bone of his bones and flesh of his flesh’ since she was formed, by God, out of a rib – both bone and flesh – that had been withdrawn from his rib-cage.

However, the narrative goes on to make a comment that is pertinent to all men and all women who were to come after Adam and Eve, that the man would LEAVE his father and mother, that he would CLEAVE to his wife, and that the two would become ONE FLESH.

This statement provides the foundation of what is both the Jewish and the Christian understanding of marriage, which we shall be considering in detail later.

But for now, what is to be our understanding of this idea of a man and a woman becoming ‘one flesh’?

First of all, let’s have a look at a statement by the apostle Paul in the New Testament. He was concerned that some members of the church in the city of Corinth were living according to the ungodly standards of the pagan culture around them rather than living to honour God:

The important point that Paul is making here is that ‘becoming one flesh’ has nothing to do with a wedding ceremony and the sharing of vows, or anything of the kind. Before God, a man and a woman become one flesh whenever they engage together in sexual intercourse.

When a couple come together in this way, a bond is formed between them which is intended by God to join them as a unit for the remainder of their lives on this earth. This is what is meant by the word ‘cleave’.

Our English word ‘cleave’ has two opposite meanings:

• a) To divide or separate into distinct parts;
• b) To adhere firmly and closely.

God clearly envisages a two-stage process, whereby there is a separation from the parents, a leaving of the comfort and security of the home of childhood and youth, and then, and only then, a cleaving together of the young couple in order to form a new nuclear family unit.

The vital point to note in this is that God intends that the young couple should not ‘become one flesh’ until they have committed themselves to marriage. The leaving precedes the cleaving.

Throughout the Bible, and in every society where the teaching of the Bible is accepted as being the basis for our moral standards, it is understood that we should observe chastity outside marriage and fidelity within.

It is also important to note that in verse 24 it says that a man (singular) will cleave to his wife (singular). The Bible therefore expects us to observe MONOGAMY – i.e. being married to one person only. More about that later, in the section dealing with marriage.

So, taking all of this together, what can we say are God’s expectations and requirements of us in relation to our sexuality?

1. The primary purpose of our sexuality is reproduction.
2. The secondary purpose is the joining of a man and a woman in a unique, ‘one-flesh’, relationship in which sexual intercourse is an essential ingredient.
3. These two purposes should be pursued together as essential elements of a single relationship (as two sides of the one coin, you might say).
4. The Bible does not envisage ANY occasion where sexual intercourse is permissible if neither of these purposes is being pursued.
5. This means that any and every other engagement in sexual intercourse is, in the eyes of God, sinful – i.e. it is outside of the bounds of what is acceptable behaviour for a human being.

Western European liberalism sees no reason for there to be any restrictions on sexual activity between consenting adults, but Christianity recognises important and strong boundaries, which have been put in place by God Himself. These boundaries are protections. They are there, not because God is a kill-joy, but because He wants us to live healthy, whole, productive, and fulfilling lives.

What, then, is He protecting us from?

There are three main problems that are constant risk factors for those who violate these boundaries, but from which those who observe the boundaries are safe-guarded:

1. Unwanted pregnancies

If you are only ever sexually active with the person you are married to, you have a secure and comfortable home environment, and a child is conceived, you are far more likely to be delighted than disappointed, and highly unlikely to be thinking about having the baby aborted.

2. Sexually transmitted diseases

In the 1980s, HIV/AIDS swept through the world like wild-fire. Why? Simple answer: promiscuity. If the man who was bitten by the monkey and contracted HIV (if that is what happened) had kept himself to himself, no-one would ever have heard about AIDS. He might have passed the virus on to his wife, perhaps their children might have become infected, but the likelihood of there ever being an epidemic would have been negligible.

While I have been writing this, in August 2025, the BBC has reported [Article entitled ‘World-first gonorrhoea vaccine rollout begins in UK as infection rates soar’, by Josh Parry, LGBT & Identity Reporter, 4 August 2025] on the roll-out of a new vaccine for gonorrhoea, which is quite a serious sexually transmitted disease. According to this report, there were 85,000 cases in Britain in 2023 – the highest since records began 100 years ago.

The journalist interviewed two men who have a history of gonorrhoea infection. One of them, a 63-year old from East Scotland, who is still suffering serious side-effects from being infected in the past, was quoted as saying, “I’m constantly looking for symptoms and I’m constantly aware of it, and I feel a bit like I used to do in the 1980s when I was constantly fretting about HIV”.

Both of these interviewees are still involved in their promiscuous lifestyles, doing what they can to try to reduce the risk of getting re-infected, and both hoping that this new vaccine will afford them some extra protection.

Of course, from the Christian point of view, the obvious question is, “why don’t you just avoid the activity that puts you at risk?” We all understand the risks involved in taking alcohol or drugs, or driving without a seat-belt, or speeding, or sending text messages while driving, and so on and so forth, and the official advice is always the same: don’t do it!

Does anyone remember the Covid pandemic of 2020 to 2022? What were we continually being told to observe? SOCIAL DISTANCING!

However, when it comes to sexual activity, nobody would dare to tell anyone to ‘socially distance’, because that would be an infringement of their human rights. Instead, lets spend millions of pounds on special clinics and all sorts of treatments and do scientific studies to see if there’s any other way to make promiscuity safe.

At the end of the day there is only one fail-safe answer to the question of ‘safe sex’: chastity outside marriage and fidelity inside marriage.

3. Broken hearts

“Tonight you’re mine completely”, wrote Gerry Goffin, “but will you still love me tomorrow?”

How many young women have been led up the garden path, and then ditched as soon as the guy scored? How many young couples have thought they were in love, only to realise that it was all icing and no cake, all froth and no coffee, and end up with a bitter taste where once was the promise of sweetness.

Sex God’s way is powerful and precious. It’s not a toy, it’s not a game, and it’s not a business. It’s an essential element of a loving, devoted, lifelong, exclusive, marriage.

But marriage also needs to be handled in God’s way, so let’s consider this vitally important subject next.