Hastings' Dictionary of the Bible (1898)
EXCOMMUNICA'TION. The writings of the Rabbins mention the various offences for which men were cut off from the privileges of the synagogue, and even from social life. " Luke 6:22. Another and yet more evident reference to these Jewish ceremonies is that in John's story of the man born blind. John 9:22-23, John 9:34-35. Rabbinical excommunication does not rest upon the Law of Moses. It is the natural outgrowth of a well-organized society, which keeps itself clear of all obnoxious persons. " It lasted 30 days, but might be renewed for an equal period.
In case of continued rebellion, the second step was taken. " The third and last step was entire exclusion from the congregation. It was to be expected that in the Christian Church the practice of excommunication would be continued. Its institution by our Lord is recorded in Matt 18:15, Matt 18:18, and the practice and commands of Paul are given in 1 Tim 1:20; 1 Cor 6:11;2 Cor 2:5-10; Tit 3:10. Christian excommunication, as we gather from these Pauline Epistles, was a purely spiritual penalty, inflicted for the good of the sufferer and in order that the church might be protected.
The sentence might be increased or lightened according to circumstances. Repentance was the condition of restoration; and as the exclusion of the offender from the temporal body of Christ was a public and congregational act, so the reception of the excommunicated member was of the same character.