Christians must be taught to cherish excommunications rather than to fear them.
The Bull of Pope Leo X against Martin Luther, 1520
Pope Leo X excommunicated the sainted Martin Luther for what what the Roman Church deemed were his error-filled teachings. The above sentence is found in Pope Leo X’s Bull excommunicating Luther from the Church, whereby he was no longer considered member of the family of God, and at this time in history, his excommunication meant he was no longer considered a “citizen” in the Holy Roman Empire. In the Bull, the Pope expressed his horror over a number of Luther’s teachings, including the one in the aforementioned quotation. Luther believed that if the church was teaching something against Holy Scripture (and it was), it was important to call the church out on its false teaching (which Luther did). On excommunication, if the church was going to continue to promote a wrong understanding of the Word of God, Luther believed that Christians who did not believe a false church teaching should not fear being excommunicated from the church, but instead, hold it dear because the Word of God would have its day and never be bound.
(Quotation is taken from bookofconcord.org)