The Watchtower says that disfellowshipping is Bible based. Critics disagree. Christians, for example say that disfellowshipping is contrary to the perfect Law of the Christ.
Disfellowshipping is the ultimate form of judgment. If it was just a matter of kicking people out of a church because they didn't measure up to the requirements of membership, it wouldn't be a big deal.
However disfellowshipping is a big deal. It is judgment in the highest form. Why? Because a 'judicial committee', decide who gets to stay in 'God's organization' and who gets thrown into Satan's world. There is not middle ground.
Disfellowshipped members are cut off from all contact with loved ones, family, and close friends (subject to some exceptions). They are shunned and treated as literally dead. Most Jehovah's Witnesses will not even make eye contact with a disfellowshipped person.
If you want to know what it feels like to be a ghost, simply get disfellowshipped and attend a meeting of Jehovah's Witnesses. The Elders might welcome you, but everyone else is trained to pretend you don't exist.
What did Jesus say about judging? Jesus said, ' Judge not, and ye shall not be judged: condemn not, and ye shall not be condemned: forgive, and ye shall be forgiven'
In spite of what Jesus said, there are a handful of Bible passages that appear to support disfellowshipping and shunning.
The Watchtower explains, 'Why is such a firm stand appropriate even today? Well, reflect on the severe cutting off mandated in God’s Law to Israel. In various serious matters, willful violators were executed. (Leviticus 20:10; Numbers 15:30, 31) When that happened, others, even relatives, could no longer speak with the dead lawbreaker. (Leviticus 19:1-4; Deuteronomy 13:1-5; 17:1-7) Though loyal Israelites back then were normal humans with emotions like ours, they knew that God is just and loving and that his Law protected their moral and spiritual cleanness. So they could accept that his arrangement to cut off wrongdoers was fundamentally a good and right thing.—Job 34:10-12.' (Watchtower April 15, 1988 "Discipline That Can Yield Peaceable Fruit" p.26 -30)
Ancient laws said that 'In various serious matters, willful violators were executed.' Are all disfellowshipped Witnesses guilty of serious wrong doing?  And even if they are, is the Watchtower Society responsible for enforcing the ancient laws of Israel? Read what the Watchtower says about Christians being under the Law of the Christ since Pentecost 33 C. E.
The reality is that the Watchtower's definition of a 'willful violators' includes anyone who challenges Watchtower authority or disagrees with any of their rules
The Watchtower says, 'In various serious matters, willful violators were executed. (Leviticus 20:10; Numbers 15:30, 31) When that happened, others, even relatives, could no longer speak with the dead lawbreaker.' (Watchtower April 15, 1988 "Discipline That Can Yield Peaceable Fruit" p.26 -30)
Is this a good excuse not to greet or have conversations with disfellowshipped Jehovah's Witnesses?
It's one thing not to be able to speak to someone because they are dead. It's another thing not to be able acknowledge, love, and respect all children of God who are living.
We don't see dead people walking down the street, or at the shopping mall, or at a local restaurant, so we can't talk with them. However disfellowshipped persons run into their relatives and former friends all the time.
Would Jesus approve of the Watchtower's interpretation of Bible passages in the old testament? See What Did Jesus Say About Disfellowshipping?
Although the Apostle Paul said, 'God will judge those outside. "Expel the wicked man from among you." ' 1 Cor 5:13, not everyone that get's disfellowshipped is 'wicked'. Many simply don't agree with all the doctrines and policies implemented by Governing Body of Jehovah's Witnesses. 
Also the Apostle Paul claimed to be a Pharisee AFTER he became the Apostle Paul. Acts 23:6. In the Bible Jesus warned his followers about the leaven of the Pharisees. Jesus rebuked the Pharisees for their self righteousness and lack of love. Mark 8:15 Luke 12:1 Matthew 16:6,11 Luke 11:42 Matthew 23:23. Get the Facts About The Apostle Paul
Not according to the Bible. See Do Not Say A Greeting and find out what the Apostle John meant in 2 John 1:10.
1. In 1 Cor. 5: 11-13 Paul says to 'expel the wicked man'. However a large majority of Jehovah's Witnesses who get disfellowshipped are not immoral or wicked. They simply disagree with some or all of the doctrines of the Watchtower. See Reasons For Disfellowshipping according the Watchtower's instruction manual for elders.
2. Is the Watchtower Society hard pressed to find support for disfellowshipping in the Bible? Some say that they are. The rumor is that the Watchtower is attempting control what Jehovah's Witnesses say and do. See Mind Control
Disfellowshipping and the threat of becoming an 'apostate' instills fear in all Witnesses. It's scary to challenge the authority of the organization because disfellowshipped persons are completely cut off from their family and closest friends.
That's why opponents say that disfellowshipping may be a Theocratic War strategy that protects the organization from harm at the expense of God fearing Jehovah's Witnesses.
3. Jesus didn't teach his followers to hate anyone. His message was love. Jesus said, "If you love those who love you, what reward will you get? Are not even the tax collectors doing that? And if you greet only your brothers, what are you doing more than others? Do not even pagans do that?' Matt 5: 46, 47 NIV.
Jesus even loved his enemies and blessed his executioners while dying a painful death on the torture stake (or cross). Luke 6:35; Luke 23:34 Also see Does God Hate?
4. Most Bible students do not teach disfellowshipping and shunning, because they don't believe it is Bible based. The Watchtower disagrees. They believe disfellowshipping necessary to keep God's organization clean.
5. Critics say that judgment, disfellowshipping, and shunning is something that the Pharisees would recommend if they were alive today. The Pharisees were concerned about outward appearances, looking clean on the outside, and appearing righteous, but they neglected the love of God. Luke 11:42 That's one of the reasons some say that Jehovah's Witnesses are not Christians. What does the Bible say? See Are Jehovah's Witnesses Christians
6. Is the Watchtower acting in harmony with what Jesus says? Christians put Jesus first, ahead of Moses, the Apostle Paul, the early Christains, and even Jehovah. Why? Because all authority in heaven and earth has been given unto him. Matthew 28:18. Jesus is the path to eternal life.
Compare what Jesus says to what the Watchtower says in this artcle: Apostate Jehovah's Witnesses