Here is what Christ intends to say: “If you see that someone despises your preaching and tramples it underfoot, have no fellowship with such a person but withdraw from him.” He says the same in Matthew 18:17: “If he refuses to listen to you and the church, let him be to you as a heathen and a tax collector.” In other words, you tell them that they are not Christians but damned heathen, and you want them to hear no preaching and to have no part in our possessions, as Peter says to Simon Magus in Acts 8:21. This is what I do, and what everyone does who takes the preaching of the Gospel seriously, in order not to make ourselves partakers of their sin. God does not want us to be hypocritical with our sectarians, as though their doctrine were correct. We must regard them as our enemies, from whom we are separated by the Gospel, by Baptism, by the Sacrament, and by all their doctrine and life. In the same way we have to say to our own people that if they want to participate in the Gospel, they must not despise us but prove by their fruit that they mean it seriously, or at least that they hold the Word and the Sacrament in esteem and humbly submit to it. (Luther’s Works, v. 21, pages 226).