This is the most important issue in the letter. Paul was preaching about the second coming of Christ as the event we should wait and hope for. The first Christians actually wanted Christ to come as soon as possible. It was even a prayer: “Come Lord Jesus!” (Rev 22:20). Paul himself expected to witness the coming of the Lord. Yet, with the passing of time the delay of Jesus’ coming became a problem. There were even some brethren who started doubting and even ridiculing this aspect of Christian message (2 Peter 3:3–4).
In the case of the Thessalonians, the problem was different. They did not doubt Paul’s preaching about the second coming of Jesus. They simply worried about their dead brethren: as dead they could not wait any longer for Jesus’ coming. What cause their death is another matter. Was it due to the persecution that they suffered? Was it due to natural causes? Whatever the reasons, Paul sets things in proper perspectives:
Christian attitude towards death and dying members of our families and communities should be different from the Gentiles. Death is not the end by the passage towards a life with God that does not know tears, suffering and another death anymore (see Rev 21:3–4). That is our Christian hope.
Those alive at the coming of the Lord will not have any advantage over those who died before His coming. Actually, the dead will precede the living. First, they will be raised, then the living will be transformed (see also 1 Cor 15:52–53). Thus, even the body of the living has to be changed - “put on incorruption” (1 Cor 15:53) - in order to enjoy the eternity with God.
These two aspects should be sufficient to console us in the face of death. We are meant for eternity. On this earth we are mere pilgrims. Our citizenship is in heaven (Phil 3:20).
It is worth noting that Paul derives this knowledge from “the word of the Lord” (1 Thess 4:15), yet nowhere we can find recorded such saying of Jesus. It is another example of the teaching of Jesus not recorded in the Gospels but preserved in other writing (see Acts 20:35).
Although Paul and many other first Christians expected the second coming of Jesus in their lifetime, the apostle himself states that the exact date of this Day of the Lord is unknown. We hear the same statement from Jesus (see Matt 24:36).
In the Old Testament, the day of the Lord was the day of God’s judgment (Amos 5:18–20; Joel 2:1). In the New Testament it is the day of Christ’s second coming, which is also associated with the Final Judgement (see 1 Cor 1:8; 5:5; Matt 25:31–46).
Whether one should be afraid of that day or await it with rejoicing depends on one’ side quality of life. Paul uses here the imagery of darkness and light, night and day. Darkness and night symbolize life in the chain of sin; light and day refer to a life of righteousness, a Christian life. Christians do not need to fear that day. As “children of light” (see also Matt 5:14), the day of the Lord will not find them unprepared. Those, who should fear that day, are those of “darkness and night”, those, who spurn God’s commandments and the preaching of the Gospel.
The phrase “peace and security” refers to false assurance that nothing bad can happen. It can be applied to the Gentiles, who live in idolatry and immorality. It can be applied to the Jews, who are so sure of God’s mercy that they do not accept any possibility of God’s punishment for their sins (see Jeremiah 36:1–32). It can also be applied to Christians, who falsify the message of the Gospel and lower its moral standards. Upon such people, the Day of the Lord will come upon unexpectedly.
Watchfulness and being sober are the mark of Christians. It refers to a standard of living according to the teaching of Jesus and constant readiness for His unexpected coming (see Matt 24:45–50).
Together with the advice of being sober, Paul tells us about Christian armor that we should put on. It is composed here of three virtues: faith, love, and hope. It is a brilliant way of ‘simplifying’ the content of the Gospel. Faith in God revealed to us by Jesus Christ and obeying the two greatest commandments of love - love of God and of neighbor - are the key components of the Gospel (see again Gal 5:6). To these two is added hope our hope of eternal salvation. If faith and love guide us firmly through this life, hope lifts our eyes beyond this life towards our promised future, namely to live with Christ forever. Because of our baptism, as God’s adopted children, we are designated not for the wrath of God but for salvation in Jesus Christ (see again 1 Thess 1:10).
If the first explanation of Paul that the living will not have any advantage over the dead at the second coming of Jesus was meant to console, the second explanation regarding the unexpected date of the Day of Christ’s coming was meant to encourage the community to preserve in their commitment to the Gospel. The hope of salvation should lead them through all trials and difficulties that faithfulness to Christ and His message often entails. Up to that time, they have been faithful; they should be faithful to the end.