Separation from the supportive head in the Body of Christ, like cutting off the Christian tree branches, is always a dangerous possibility for the proud and disobedient limb.
Like a once normal but now cancerous cell, the rebellious part becomes a threat to the others. Paul warns the Colossian church of this possibility in Colossians 2.19, "He has lost connection with the Head, from whom the whole body, supported and held together by its ligaments and sinews, grows as God causes it to grow."
As in the parable story of the vine and the branches, contact with Christ can be severed for ever. Jesus says in John 15.6, "If anyone does not remain in me, he is like a branch that is thrown away and withers." Christ himself and not the other tree branches separate the dead part from the tree to allow the rest to grow on unimpeded.
Jesus also described the fake Christian as a goat in a flock of sheep. In Jesus' day, there were both sheep and goats in any flock. The chief difference was the goats went "butt, butt, butt.."