Gerhard and Walther

Rather, you have received them so that you use them solely to the glory of God and for the building up of the Christian Church. Great gifts do not make a person great and acceptable before God; instead, the proper use of these gifts pleases Him. Wherever such proper use of these great gifts does not exist, they can more readily be harmful than helpful to one’s salvation.—Johann Gerhard, Schola Pietatis, I:136, 137.

If members of a Christian congregation openly commit sins and, with impenitence and stubbornness, want to persist in them, the Church has the duty to cut them off as rotten and dead members from its body. It must announce to them God’s wrath and eternal condemnation, regard and declare them to be heathens, and avoid fellowship with them. In short, it must excommunicate them.—C. F. W. Walther, God Grant It!, p. 181.