The term itself, "to disfellowship," is no longer used in the Seventh-day Adventist Church Manual. The word has been replaced with the phrase "to remove from membership." However, both the word and the phrase mean the same thing.
It is true that the church should always demonstrate forgiveness and acceptance of the individual sinner. But some behaviors are so violent, destructive, and evil that the church must take a public action that notifies everyone--whether they are members in the church or those from the world who are observing the church--that such behavior cannot be tolerated within the body of believers.
Paul's letter (1 Corinthians 5:1-13) tells the church in Corinth to discipline members with a view to redeeming them (or restoring them to fellowship). But sometimes it’s necessary to remove the unrepentant from church fellowship so that the reputation of the whole church is not threatened by the rebellion of a few.
Certainly it would bring reproach on the church if an individual who abused little children, or someone who murdered, or someone who lived a sexually immoral life, was allowed to remain a member in good standing. People would assume that because the behavior is tolerated, even endorsed.
An intermediate step of discipline, prior to "removal from membership," is "censor" in which a person remains a member, but is not permitted to exercise leadership or to represent the church for the specific period of time for which they are censored. The conclusion of that time should bring either repentance and restoration or, for those who remain in rebellion against the clear teachings of God's word, "removal from membership."
Why are there so many different denominations?
Jesus prayed that His followers would be united (John 17:11), but this has not been the case. As the church expanded, factions began to grow. For instance, Paul complains about them in the church at Corinth (1 Corinthians 1:12, 13). Some in the church at Corinth were following individuals and their emphasis. Some denominations have developed through the work of strong individuals: Martin Luther (Lutherans), John Wesley (Methodists) and John Knox (Presbyterians). Some denominations grew out of Bible truths they emphasized: Baptists emphasized adult baptism and, of course, Seventh-day Adventists emphasized the seventh-day Sabbath and the Advent (Second Coming) of Jesus.
Almost all denominations have grown out of a split within Christianity. The Reformation saw the greatest divide of all, when Protestantism broke from Catholicism. Since then, almost all denominations have been formed as they broke away from others. An exception is the Seventh-day Adventist Church, which grew out of a movement that involved people from most Protestant denominations in North America.
Sometimes a new denomination formed because of conflict in a church, but sometimes it formed because the old denomination could not see the new biblical truth that had been discovered. The lesson for us, as a denomination and individuals within our denomination, is to remain focused on biblical teaching and remain open to new understandings of biblical truth. That’s something you’ll find emphasized in the introduction to the Adventist Church’s fundamental beliefs.