Jehovah's Witnesses practice disfellowshipping based on the words of the Apostle Paul who said, 'But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat.' 1 Cor 5:11 KJV Bible  They also refer to Edward Gibbon to justify disfellowshipping.
However Raymond Franz in his 700 page book 'In Search of Christian Freedom' presents factual evidence that the organization uses Paul's words as an excuse to disfellowship everyone who disagrees or challenges their doctrines. Their only sin is interpreting the Bible differently than the Watchtower Society.
Mr Franz served on the Governing Body of Jehovah's Witnesses for nine years. According to him, Witnesses who want to worship God directly and exercise their conscience based on God's Word, receive the same punishment as the evil doers Paul spoke about. 
Some Witnesses who disagree don't want to leave their religion or cause trouble. Others want to leave 'quietly', so that they can continue to have a relationship with their family and friends. Disfellowshipping and shunning makes this impossible. See Why Don't Jehovah's Witnesses Leave Quietly
If there was an honorable way to leave the Watchtower Society, all people would leave 'quietly'. All people want is respect, love, and kindness. They don't want to be called apostates and treated as if they are literally dead. When a religion is an example of God's love, they are loved in return. Matthew 7:1
More Facts About Disfellowshipping
1. Paul openly admitted to being Pharisee AFTER he became the Apostle Paul! Get all the Facts About The Apostle Paul. Find out why some of Paul's teaching conflict with the teachings of Jesus.
2. In Search of Christian Freedom, by Raymond Franz, 2007. Commentary Press, Atlanta, GA. See 'The Misuse Of Disfellowshipping' Chapter 11 Pages 348 - 390.