Sunday, the first day of the week, is considered the rest day for many. For Christians, it's considered the Lord's Day, a day to come together to worship God, the Father of our Lord Jesus Christ. Of all the days in a week, why do Christians go to church to worship God on Sunday? Let's take a quick look.
An institution since the beginning
The Bible records for us that after working six days in creation, God rested on the seventh day and blessed it and made it holy (see Genesis 2:2-3). God wanted His followers to follow this very pattern, and commanded that men should work six days and rest on the seventh day like He did.
"Remember the Sabbath day and keep it holy. Six days you shall labor and do all your work, but the seventh day is a Sabbath to the Lord your God. On it you shall not do any work, you, or your son, or your daughter, or your male servant, or your female servant, or your livestock, or your sojourner who is within your gates. For in six days the Lord made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy." (Exodus 20:8-11)
This seventh-day rest has been instituted since the beginning. God's people, those who lived before Jesus Christ came to earth, followed this. In fact, Jews strictly followed this and allowed no form of work whatsoever on the Sabbath day.
An institution fulfilled
After Christ came, however, this changed. Christ, who came to fulfill the Law and not abolish it (see Matthew 5:17-20), accomplished for us what we cannot do by ourselves: our salvation.
God's command for man to rest on the Sabbath was included in the Old Covenant, by whom no man could be saved (Heb. 7:11-12, 18-19; 8:7, 13). Christ, however, fulfilled all the Law and in doing so purchased our salvation for us: His blood shed on the cross for the forgiveness of our sins and His death in exchange for our eternal life (see 1 John 2:2).
A new institution
So why do Christians worship on Sunday? It's because of Christ's finished work. He died for our sake, and rose later on the third day, a Sunday.
"Now on the first day of the week, very early in the morning ... They found the stone rolled away from the tomb. But when they entered, they did not find the body of the Lord Jesus ... suddenly two men stood by them in shining garments ... they said to them, "Why do you seek the living among the dead? He is not here, but has risen!"" (see Luke 24:1-6)
Since the time Christ rose from the grave, His followers began meeting on the first day of the week, Sunday. They had communion on Sunday (Acts 20:7), gave their gifts on Sunday (1 Corinthians 16:1-2), and eventually called Sunday "the Lord's Day" (Revelation 1:10).
While the Old covenant required God's people to gather on the Sabbath, the New covenant that assures us that we can rest on the finished work of Christ (see John 19:30; Hebrews 4:10) and celebrate His resurrection on the first day .