Some would say that Christians worship on Sunday because it was the day of Christ's resurrection. Others might refer to Acts 20:7, which says, 'Now on the first day of the week, when the disciples came together to break bread....' This, they would say, indicates that the early believers worshiped on Sunday (even though it only says they came together to eat). The truth is, Sunday worship is a tradition instituted by the Roman Catholic Church.
In 321, Emperor Constantine issued an edict outlawing work on the 'venerable day of the sun' (Sunday). Within three years the corrupted Roman version of Christianity had become the official religion of the Roman Empire. In order to clearly distinguish the so-called Roman Christians from the Sabbath-keeping Jews, and because Sunday was already set aside as a day of rest, it became the official day of worship.
Today most apostolic churches meet on Sunday primarily because of tradition, but also because it is the one day of the week when most people in America are off work and available to get together. There is no spiritual significance to Sunday. As Roman Catholic Cardinal Gibbon admitted in his book Faith Of Our Fathers, 'You may read the Bible from Genesis to Revelation, and you will not find a single line authorizing the sanctification of Sunday. The Scriptures enforce the religious observance of Saturday, a day which we never sanctify.'
So the question is, should Christians change their day of worship to Saturday? For a detailed answer to this question, please see our article titled 'The Real Meaning of the Sabbath' in the Apostolic Free Library. You can find it at http://www.gloriouschurch.com/html/The-Real-Meaning-Of-The-Sabbath.asp.