Christian worship on Sunday has a significance which goes well beyond merely encouragement, fellowship and corporate worship. This significance is related to the designation by the early church of Sunday as the Lord’s Day. To grasp what this means we must begin in the Old Testament. The Old Testament prophetic books speak about the Day of the Lord. The Day of the Lord described by the prophets is a day to be feared by all (Isa 13:6; Ezek 30:3; Joel 2:1, 11) because on that day sin will be judged (Isa 13:9; Obed 1:15). The New Testament also speaks of the Day of the Lord, but this phrase takes on a new meaning there. Since in the New Testament the Lord generally refers to the Lord Jesus Christ, in 1 Thess 5:2 the Day of the Lord (which will come like a thief in the night) describes the return of Jesus (4:15-5:1). But it is still a day of judgement on sinners.
The New Testament refers to the Day of Judgment in many different ways. It is the Day of Judgment (Matt 10:15; 11:22; 12:36; 2 Pet 2:9; 3:7; 1John 4:17); the day of wrath (Rom 2:5); the day when God will judge the secrets of people (Rom 2:16); the day of Christ Jesus (Phil 1:6); the day of Christ (Phil 1:10; 2:16); the day of the Lord Jesus (1 Cor 5:5; 2 Cor 1:14); the day of our lord Jesus Christ (1 Cor 1:8); the last day (John 6:39, 40, 44, 54; 11:24; 12:48); that day (Matt 7:22; 26:29; 2 Tim 1:12, 18; 4:8); The Day (1 Cor 3:13; Heb 10:25; 2 Pet 1:19); the day of visitation (1 Pet 2:12); the day of God (2 Pet 3:12); the day of eternity (2 Pet 3:18); the great day (Jude 1:6); and the day of redemption (Eph 4:30).
While all these passages refer to the same day, they do not refer to it in the same way. In some passages mention of that day are positive and something which we must look forward to. For example, Paul tells the Corinthians he will boast of them and they of him on the day of the Lord Jesus (2 Cor 2:14). Paul is confident about that day because he says, “I know whom I have believed, and am convinced that he is able to guard what I have entrusted to him until that day” (2 Tim 1:12). Some passages speak of that day in a fashion which should cause fear in the sinner. Jesus said in John 12:48 that the very words he spoke will, on the last day, condemn those who rejected him. That day will be a day of wrath for the unrepentant (Rom 2:5). Some passages put the two together – wrath for the unbeliever and rescue for the righteous (2 Pet 2:9). Therefore the Lord’s Day can bring either wrath or salvation.
The difference between confidence on the Day of the Lord and fear of wrath is based on union with Christ or rejection of him. “For my Father’s will is that everyone who looks to the Son and believes in him shall have eternal life, and I will raise them up at the last day” (John 6:40). In John’s Gospel eternal life is very much connected with both faith in Jesus and resurrection on the last day (John 6:39, 40, 44, 54). The connection between the day of the Lord and resurrection is important. Salvation is inextricably linked with the resurrection of Jesus. Jesus said as much in the predictions of his death. “From that time on Jesus began to explain to his disciples that he must go to Jerusalem and suffer many things at the hands of the elders, the chief priests and the teachers of the law, and that he must be killed and on the third day be raised to life” (Matt 16:21). Paul writes that the gospel which saves us is most fundamentally that Jesus died, was buried and rose again on the third day (1 Cor 15:1-4). It is the resurrection of Jesus which accomplished our justification. “He was delivered over to death for our sins and was raised to life for our justification” (Rom. 4:25).
And it is the resurrection which transforms the early church’s understanding of the Lord’s Day. In the last book of the New Testament John was in the Spirit on the Lord’s Day when he had a vision (Rev 1:10). Although this is the only mention of the Lord’s Day as a day of worship in the New Testament, the early church Fathers certainly used the term “Lord’s Day” to refer to Sunday, the day of worship. Ignatius Bishop of Antioch (died c 115 AD) wrote, “We have seen how former adherents of the ancient customs have since obtained a new hope; so that they have given up keeping the Sabbath, and now order their lives by the Lord’s Day instead” (Ignatius to the Magnesians 9:1). The Didache (c 80 AD) also mentions Christian worship on the Lord’s Day. “Assemble on the Lord’s Day, and break bread and offer the Eucharist; but first make confession of your faults, so that your sacrifice may be a pure one” (Didache 14:1). This change from worship on the Sabbath (Saturday) to Sunday has to do with the fact that Jesus rose from the dead on Sunday. Sunday has become the day of the resurrection and the church began to refer to this day as the Lord’s Day.
Since the Lord’s Day is a designation for both the Day of Judgment or the Last Day and the day of worship or the day of the resurrection, this suggests a strong connection between the resurrection of Jesus and the Day of Judgment. The New Testament makes this connection explicit. “For [God] has set a day when he will judge the world with justice by the man he has appointed. He has given proof of this to everyone by raising [Jesus] from the dead” (Acts 17:31). In other words, the resurrection of Jesus points clearly to the Day of Judgment, since his resurrection guarantees that that judgment will definitely occur. But this connection between the Lord’s Day as Sunday worship, the day of the resurrection of Jesus, and the Day of Judgment implies something about the gathering together of Christians each Sunday.
In gathering together on Sunday and celebrating communion or the Lord’s Supper we “proclaim the Lord’s death until he comes” (1 Cor 11:26). Implicit in proclaiming the death of Jesus is proclaiming his resurrection. Sunday worship by believers, then, proclaims the resurrection of Jesus. But if we proclaim his resurrection then by extension we also proclaim the Day of Judgment. This day holds no terror for those who trust in the death and resurrection of Jesus as the basis for their salvation and the promise of eternal life. For believers that day will be a day of blessing when we see Jesus face to face. For this reason we long for his appearing (2 Tim 4:8). However, that day will be a fearful day for those who are not united to Christ.
What this implies about Christians gathering for worship on Sunday is that if we are truly proclaiming the death and resurrection of Jesus in our words and actions (in the Lord’s Supper) then this is bound to make some people extremely uncomfortable. They are uncomfortable because the resurrection of Jesus implies a sure Day of Judgment. What is problematic is that as Christians we try hard to make everyone feel comfortable on Sunday. Perhaps we do this because we want people to stay in church and feel welcome. Perhaps we are afraid that the truth of what the gospel exposes in people will turn them away from church and our churches will empty out. If indeed everyone is comfortable in church on Sunday, then we are not actually proclaiming the Lord’s death until he comes, nor speaking truthfully about his resurrection and what this implies. Being comfortable in church might make us feel good in the present, but we cannot celebrate the Lord’s Day without the discomfort produced by the resurrection of Jesus.