Shunning is a widely-known yet controversial social practice of the Old Order Amish.  How do the Old Order Mennonites, close spiritual cousins of the Amish, approach the matter?  An excerpt on the topic:

“Members who stray from the teachings and practice of the church are reprimanded by the deacon.  Persons who refuse to cooperate with the church may be “set back” from communion.  If they remain stubborn and unyielding to the Ordnung and the counsel of elders, they will face excommunication.  Sometimes a person may continue to attend services but refrain from communion if he or she participates in a forbidden practice.  In the Ontario Conference, a number of persons who smoke tobacco attend worship services, but they do not commune because smoking is a test of membership.  These persons participate in the life of the community but technically are outside the fold.  In eastern Pennsylvania, smoking is “testified against” but is not a test of membership, and hence members who smoke are able to commune.  More serious offenses–owning an automobile or divorcing a spouse–will bring excommunication if the deviants fail to repent.  Mennonites generally do not shun excommunicated members as severely as do the Amish.  Several independent groups of team Mennonites do practice social avoidance, but the larger groups do not.  Nevertheless, excommunicated members will feel the stigma of shame.”

(From On the Backroad to Heaven: Old Order Hutterites, Mennonites, Amish, and Brethren, by Donald B. Kraybill and Carl Desportes Bowman)