Many Protestant sects of Christianity use this term to mean something milder than the Jehovah's Witnessess mean. As far as I can tell, it largely means that the person disfellowshipped is not a member of the church any more and isn't particularly invited to come back unless he/she reforms.

Related ideas are excommunication, which is practiced by the Catholics; shunning, which (IIRC) is practiced by the Amish; and Suppressive Person declaration, which is practiced by the Scientologists.

Dis*fel"low*ship (?), v. t. [See Fellowship, v. t.]

To exclude from fellowship; to refuse intercourse with, as an associate.

An attempt to disfellowship an evil, but to fellowship the evildoer. Freewill Bapt. Quart.

 

© Webster 1913.