Read or listen the First Epistle to the Thessalonians - chapter 4 online (ESV, Bible Gateway)

How should a Christian live? 4:1–12

In all his epistles, Paul speaks of how Christians should live. He teaches uncompromisingly that man is saved by grace alone, through faith, because of Jesus. This does not rule out the teaching of ethics. Christians are God’s children, not because of their own works, but because the Lord has adopted them by grace. However, it does not mean that a Christian gets to live in any way. Precisely because God has by grace adopted us as his children, we may and can do his will in our lives.

Even when he was in Thessalonica, Paul had taught how the church should live. Now he repeats his teaching. Man will never know God’s holy will too well. Paul is not reminding the Thessalonian Christians of the teaching on the supposition that the congregation is living strikingly against the will of God. If that were the case, he would not speak as gently as he does now. Perhaps the apostle has Thessalonica and its life on his mid. In the introduction, we noted that the city was a major port. Life near a port is often far from God’s will. Paul wants to keep Christians apart from this. They should not live like others.

Paul’s teaching is very practical. In verses 3-8, the apostle presents things that Christians must not indulge in. First, Paul reminds the church of the sixth commandment. Christians must not live their sexual life in whatever way. Marriage is sacred and must not be defiled by love affairs. The apostle's reminder is not just for those who are married. At that time, it was customary to throw wild parties rife with immorality. Paul commands the Thessalonian Christians to stay away from immoral activities. A Christian must keep his body holy and not give it into the service of sin. The passion of lust must not control it, but the Christian must live and act differently from the Gentiles. Because the Gentiles do not know God, they do not care about God’s will. Christians, on the other hand, are children of God and therefore they must not forget the commandments of their Father.

In verse 6, Paul forbids tyrannizing brothers. He may be talking about money matters in which greed may easily overcome honesty and brotherly love. Paul can also be referring to legal actions in which a Christian oppresses another Christian by the law. The oppressor will face God’s punishment – possibly even in the present time, and before the judgment seat of God at the latest.

In verse 7, the apostle sums up what he said above: we must not live in sin. God wants us to live a holy life. Paul speaks of holiness in many of his letters. We need to note a significant difference between two matters:

Paul teaches that a Christian is completely holy even now. Otherwise, we could not please God who requires perfect holiness. However, we are not completely holy by our own lives, but our holiness is the holiness of Christ. When we are baptized and believe in Jesus, we have the holiness of Jesus and are therefore holy in the eyes of God.

At the same time, Paul is talking about another holiness. By this he means our lives and how well God’s will is fulfilled in our lives. This holiness will never become perfect in this present time. We will be imperfect until the end. Nonetheless, our goal is to lead a life as holy as possible, that is, in accordance with God’s will.

Paul ends his talk of what is not allowed with a serious warning. If you disregard the instructions of the apostle, you do not reject the commandments of man but of God. If you reject the commandments of God, you reject God. If you reject God, you reject the Holy Spirit. Without the Holy Spirit, no one can be a Christian. We must not draw a wrong conclusion from this warning. Paul does not mean that a Christian who falls into some single sin loses the Holy Spirit. The warning speaks of a distinct turning of your back on the commandments that Paul communicates to us from God.

In verses 9-12, Paul continues explaining how Christians should live. Now he is not talking about what we must not do, but what we must do. Paul speaks of the brotherly love that the church of Thessalonica shows in an exemplary way. God has given the Christians of Thessalonica the Holy Spirit. The Spirit of God causes love to grow in the church. This is how God himself has taught the church. Love for brothers and sisters of faith is not limited to the Thessalonian Christians’ own congregation, but they also show love for members of other congregations. We are not told how they were doing it. Paul speaks only in general about showing love. For the recipients of the letter, this has certainly been enough; they understood what Paul means.

The recognition that the Thessalonians receive from Paul does not mean that the church would have become perfect in showing love. There is still room for improvement. We will never become perfect in this world. The good fight for the better will continue until death; only when we arrive in heaven is imperfection gone.

In the church of Thessalonica there were members who despised work. They thought it was much finer to act as spiritual leaders of the church and devote themselves so entirely to serving God that there was no time left to earn their living. However, those who thought so did not live without food, housing, and clothing, but others had to pay these for them. Paul wants to put an end to this kind of Christianity. The Christians must provide for themselves, and no one has the right to live at the expense of others. Nothing is more valuable than the fact that a Christian carries out his daily work conscientiously. We should not misunderstand Paul's teaching. If some people are unable to support themselves e.g., due to old age, illness, or unemployment, they can, of course, receive help from others. Nor does Paul teach that there should not be any church members who do only spiritual work and receive their salary from other members of the church. Paul clearly states that those who are in the ministry of the word should get their living from their work (1 Cor. 9:14).

However, not just anyone may become a minister of the word, but it is for those who God and the church have called to take care of the task. In verse 12, Paul sets a high goal for Christians. We must live so that also those outside the church could admit that we are blameless. This is what the apostle means when he speaks of decency towards those outside. At the end of the verse, Paul gives a special instruction: he hopes that Christians will not need anyone’s help. The instruction should be understood on the grounds of what has been said above. A Christian must not live off others.