The central error of modern thinking, surely, is that today men and women imagine that they have the right to decide for themselves, anew and afresh, what Christianity is, what the church is, and what her message is. Now this is not only presumption, it is unutterable folly, because we are dealing here with something that is historical. If we really want to know what Christianity is and what the Christian church is, then in common honesty, there is only one thing to do, and that is to go back to the record.

We have been considering the account in Acts 2 of these early Christians. The words and expressions used here were not chosen at random. They were inspired by the Holy Spirit himself. And we have here the marks and characteristics of the true Christian. The moment men and women become Christians, these are the ways in which they show it. And we come now to one of the most interesting: 'They did eat their meat', not only with glad­ness, but also 'with singleness of heart'.

This most important statement means, first and foremost, that these Jerusalem Christians were all of one mind, that they were experiencing a wonderful unity. 'Singleness of heart'! Their hearts, as it were, were melted into one another. It is a description, then, of the company, the society, of these believing people looked at in general. Our Lord had prayed that his disciples might be one, even as he and his Father were one (John 17:21), and here they were giving expression to this oneness. They had different temperaments, different backgrounds, different upbringings. They differed in almost every conceivable way, yet they were all melted into one in this extraordinary unity.

Why were they manifesting this great unity? They showed this singleness of heart because each one of them separately had a single heart. Each one had been made a unit, had been unified. This is one of the most remarkable things about the gospel, and it is one of the greatest characteristics of the Christian life.

Our Lord said,

The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light. But if thine eye be evil, thy whole body shall be full of darkness.Matt. 6:22-23

There is this same expression – 'if thine eye be single'. What does our Lord mean by that?

It is a great principle that when men and women believe the Christian gospel, the main effect it has upon them is to unify their life, to make them 'single'. Men and women apart from Christ and outside the life of God, have double vision. They do not see things properly. They do not see them unified. They do not see them steadily and as a whole. What Christianity does is get rid of the complications and produce an essential simplicity.

The effect of Christianity is always to simplify, to make single. We see it in the history of the Christian church. Here is a lyrical picture of the church at the beginning. The believers went at first to the temple because they had been brought up to do so and it was available for them to have their meetings. But that was supplemented by their meeting together in one another's houses – 'breaking bread from house to house' – and we read in the epistles about 'the church that is in their (Priscilla and Aquila's) house' (Rom. 16:5), and so on. That is primitive Christianity. We, of course, inevitably tend to think of the church as some great institution with buildings and people dressed up in robes, and pomp and ceremony and processions. How different it has all become from what you find here in the second chapter of Acts.

How has the church ever developed into an institution? There is only one answer – people have done all that. They always make everything compli­cated... But the gospel always gets rid of complications. It says that God's way is the way of singleness of heart, the single eye. Complications are man's doing; simplicity ever characterizes the true gospel.

And look at this in the case of the individual. The unbeliever's life is a complicated life. Sin always introduces complications. This is all to be seen in Genesis 3. When Adam and Eve sinned against God, they had to run and hide. They could not face God. They needed protection. Already the compli­cations had come.

Then, because of their sin, they were driven out of the Garden, and had to earn their bread by the sweat of their brow. We read about Cain starting to build cities. This was the beginning of civilization with all its compli­cations. Sin makes life complicated and difficult because it divides up our lives into sections. We no longer have a unifying principle. Do you not see that in life today? Human beings are the most contradictory creatures on the face of the earth, on one side, brilliant in their achievements, and on the other, so often despicable in their living. Mastering the elements, they are unable to master themselves. There are warring elements and factions within them.

Now we have all found this out from experience. The apostle Paul ex­presses this problem perfectly in Romans 7 where he talks of this duality that is in us: 'To will is present with me; but how to perform that which is good I find not' (Rom. 7:18). 'For I delight in the law of God after the inward man: but I see another law in my members, warring against the law of my mind' (verses 22-23). That seventh chapter of Romans is the most profound psychological analysis of man without God and without Christ that has ever been written.

Paul says in effect, 'I am at least two "I's". There is an "I" that wants this; there is the other "I" that wants that.' And he seems to be outside both of them. He looks on at these warring elements in his personality and he does not know what to do, so he cries out in despair, 'O wretched man that I am! who shall deliver me?' (verse 24). Now that is the effect of sin ­complications, divisions, warring elements. But the moment people believe the gospel, singleness comes in – 'singleness of heart'. Order is brought into the life. A principle is introduced which governs everything. Life is made whole. That is what happened to all these people in Acts 2.

This is something that is given to us by the Lord Jesus Christ... How does our Lord do this? How does the Christian life become simple and single? First of all, this principle is introduced into the mind. The first thing people discover when they become Christians is that there is only one thing that finally and ultimately matters, and that is their soul. Look at the world today. Look at the thinking people. Read the more intelligent journals and the books that come out dealing with the problems of society. I do not want to say a word against them, these are absolutely essential. Government and order are ordained of God.

But the trouble with people who are not Christians is that they begin to examine a problem piecemeal. One says, 'I must examine that.' Another says, 'No, it is this.' There they are, setting up commissions of enquiry, sub­committees and more sub-committees. But they never arrive even at an understanding of the problem, quite apart from a solution. And this is where the gospel is so different from every other teaching. It comes immediately to the centre and says, 'There is only one thing that matters, it is your soul.'

The story about our Lord in the house of Martha and Mary illustrates this well. 'Martha,' our Lord said, in effect, 'the trouble with you is that you are distracted, you are trying to do this and that. You have invited me into your house, but now you are concerned about giving me a meal instead of listening to what I have to say. Martha, you are divided up. Mary has the single idea. One thing is needful, and one thing only.'

Our Lord was constantly saying this. Listen to him on another occasion: 'What shall it profit a man, if he shall gain the whole world, and lose his own soul?' (Mark 8:36). This is the tragedy of the twentieth century, the age of encyclopaedias. What knowledgeable people we are! How ignorant our forefathers were!

Why do we fail, then? What is the matter with us? And that is the answer: What shall it profit a man if he gain the whole world of knowledge and wealth and everything else, and lose his own soul? Our Lord emphasized this from the beginning, there in the Sermon on the Mount.

He says,

Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat.Matt. 7:13

Now there Jesus is not only talking about morals, but about thought also. If you want to know a 'single-eyed' life, if you want this essential simplicity that characterized Christianity, you must start with the mind and in this way you enter in at the narrow gate. This means recognizing that nothing matters but the soul.

And that is what happened to the people listening to Peter on the day of Pentecost. Oh, they had their interests and they talked about them, but as they listened to Peter they had come to the realization that there is only one thing that matters. They said, 'What does it matter what I think about the Roman government or about my wealth or learning? When I am on my deathbed, nothing will matter to me except God and myself and the relation­ship between us.' That is the way in which our Lord simplifies everything and produces this singleness of heart.

And this is still the truth. The world is busy with its learning but there is still only one fundamental question that we need to face, and it is: How can I stand before God? The world and its kingdoms are passing away: 'Change and decay in all around I see.' Every day I get a day older and I know that the time is inevitably coming when I shall be alone with God. So the gospel simplifies the problem, does it not? It tells us that all the teeming problems in the world have arisen directly because men and women have lost the face of God, and are sinners in his sight, and under condemnation. Do you know that it all comes to that? Alcoholics Anonymous meetings, marriage guidance councils – so many groups are being set up to deal with this and that problem, but if men and women were only right with God, we would not need one of them. All the problems would be solved because they all stem from this evil that is in humanity as a result of its wrong relationship to God. That is why the gospel talks about singleness of eye and singleness of heart – this great principle of unification.

Now these people in Acts had come to that. But, thank God, it does not stop at merely isolating the one question that matters. Christians have not only been given to see the one problem that confronts them, they have also found the one and only answer, and this is what, if I may say so, I rejoice in at times more than in anything else. Christians are people who are no longer seeking; they are people who have found. They are no longer swayed by different views and ideas and schools of thought. They are no longer waiting on tiptoe for a book that is to be published next week which they are assured by the publishers will be of great help. No, they say, 'I've got it. I've already found it.'

Christians have found the answer: it is in this one blessed person, Jesus Christ. There is no other answer. The seeking and the questing and the striving and the searching have come to an end. They know that Christ is the Son of God. He is the one who brings us to God. And we have already seen how Christ brings us to God by himself taking the punishment for the sin that separates us from a holy God.

Here is an end to the old restlessness and lack of peace. What a terrible thing that is. We have all known this, have we not? You remember that famous, often quoted statement of Augustine – and it can never be repeated too frequently – 'Thou hast made us for thyself, and our hearts are restless until they find their rest in thee'? The whole universe cannot satisfy us. We can have wealth in abundance, we can have possessions, and learning, they will not give peace and rest of heart.

Have you not known something about that restlessness? The world cannot satisfy us. Why not? Because 'God has put eternity in the heart of man' (Eccles. 3:11, RV). Thank God, human beings are too big and too great to be satisfied by anything in this world. The whole world is looking for the quiet heart, the rest, the peace that the world can neither give nor ever take away when it is truly given by Christ.

But when men and women come to Christ, the restlessness goes. This is what had happened to these early Christians. It all went away – that old restlessness, that feeling that they wanted something else, that there is always a fly in the ointment, that there is no final satisfaction, no real peace. Now they were no longer divided within themselves as to what they ultimately wanted. Now they had peace because they had singleness of heart.

Our Lord has expounded that so fully in the Sermon on the Mount that I have nothing to do but to quote him. He said, 'Ye cannot serve God and mammon' (Matt. 6:24). That is the whole trouble with most people, with all people, indeed, who are not in Christ – the divided heart.

So your heart is divided and distracted and you cannot sleep and you have to take more sleeping pills, and then you need a stimulus to enable you to live the next day. You are all divided. You are a mass of contradictions and you do not know what you want. There is this conflict: God and mammon; heaven and earth; time and eternity. Which shall I live for? We do not know which is most important. All that is done away with in Christ.

Furthermore, the heart is restless and divided because of self. The ultimate cause of all this heart restlessness is self. I set myself up, and that means doing somebody else down. There is conflict, jealousy, envy, despising, hating, ambition, desire – what a terrible business it is! And then the heart is divided against itself. But the moment men and women come to Christ, they get a single heart. It all happens in Christ.

Once men and women really know Christ and his salvation, they are given a final satisfaction. The world may rob them of everything, but Christ remains. So the apostle Paul was able to say,

I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come, nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.Rom. 8:38-39

Again, when he was an old man in prison in Rome, Paul heard a rumour that the emperor Nero had decided to put him to death at any time. How did Paul write about it all to the Philippians? He said: It's all right. Don't be worried about me, 'For to me to live is Christ' (Phil. 1:21). Christ is life to me.

Finally, the need for singleness applies also in the realm of the will. What is our aim? What is our motive? What is our object and purpose in life? There are millions of people who are unhappy because they have the wrong aims to get on and cut great figures, to leave their names on the pages of history. But, 'Uneasy lies the head that wears the crown,' said Shakespeare. There is nothing that so troubles a man or woman as worldly ambition, muddle and confusion in the realm of motives and ideas.

But the moment someone believes in Christ, that person has singleness in the will as well as in the mind and heart. Each Christian has one great desire. It is, 'That I may know him, and the power of his resurrection, and the fellowship of his sufferings, being made conformable unto his death; if by any means I might attain unto the resurrection of the dead' (Phil. 3:10­11). That was the apostle Paul's sole ambition – 'That I may know him'. And anyone who knows anything about him gets consumed by this great passion.

Take my will, and make it Thine,
 It shall be no longer mine.
Francis Ridley Havergal

That is the prayer of Christian men and women. They have singleness in the realm of the will. They have one idea, one desire, one motive, and that is to live to his praise who has died for them and opened the gateway of heaven to them. The whole of life becomes simple; the programme becomes a simple one. John Wesley said, 'I have become a man of one book,' and in a sense that is true of every Christian. Have you discovered that all the books in the world cannot help you unless you know this? This one aim will bring you to one book. It will bring you to one person, to one death, to one resurrection, to one hope, all in Christ Jesus. Here is the explanation of the singleness of heart of the Christian.

So there remains one question: Have you got this singleness in your mind, in your heart and in your will? The world knows nothing about it. The world is typified by Martha – cumbered, distracted, rushing about, fussing, and missing everything. The Lord of glory is there, and there she is, busy. He has not come to eat, he has come to teach. Come, have you sat at his feet as Mary did? Is this your prayer?

O that I could for ever sit
Like Mary at the Master's feet.
Be this my happy choice.
My only care, delight and bliss
My joy, my heaven on earth be this,
To hear the Bridegroom's voice.Charles Wesley

So stop rushing about, stop reading, stop arguing. Take your seat with Mary at the Master's feet. Listen to him and he will say to you,

Come unto me, all ye that labour and are heavy laden, and I will give you rest. Take my yoke upon you, and learn of me ... and ye shall find rest unto your souls.Matt. 11:28-29