Traditionally the Reformed church has acknowledged there to be up to three marks or signs of the true church: the pure preaching of the Word, the right administration of the sacraments, and the faithful exercise of discipline. With a disruption in the ecclesiastical unity of the Western church, it was vital to establish a way to distinguish between true churches and false churches in a landscape that included the Church of Rome, various new Protestant churches, and other sects. Over against the Church of Rome, the Reformers had to support the argument that their churches bore the marks of being a true church. While the Papists put forward up to fifteen marks defending the Roman tradition and hierarchy, such as its name and antiquity, (see Bellarmine’s Controversiis, III, 10), the Reformers “presupposed that the church was not trustworthy in and of itself, that [it] could stray and depart from the truth, and there was a higher authority to which it too had to submit.” That authority being the Word of God.
Now we had noted that there were up to three marks of the true church. Some Reformers, like Calvin, did not include discipline as a separate mark, believing it to fall under Word and sacrament (see Institutes 4.1.9). Others went one step further and did not see a need to have any marks in addition to the Word, since the Word is that which is “variously administered and confessed in preaching, instruction, confession, sacrament, life, and so forth.” It seems fitting and useful to maintain the three marks, for we would not think highly of a church that did not practice the basics of rightly administering the sacraments or exercising church discipline. That said, it is certainly true that all the marks can be summed up in the Word. In his Systematic Theology, Louis Berkhof wrote that, “The Word is truly the soul of the church. All ministry in the church is a ministry of the Word… In the one mark of the word the others are included as further applications.”
But what do we mean by “pure preaching” and “right administration”? What if a preacher teaches error? What if the church uses grape juice instead of wine? Swiss Protestant theologian Johannes Wolleb explains that we do not need to become worked up over whether a certain church is a true church because some error is present, for “such purity is not required, whereby there is no error in a single article, or no abuse creeps into the administration of the sacraments.”Perfection is not attainable in this life. So where is the line that delineates between a true church and a false church? Wolleb said that charity should be given to a church in error especially if the church does not retreat from “the pivot of salvation, namely the two tables of the law and faith in Christ.” Berkhof wrote that there is a limit beyond which a church cannot go in its denial of the truth, such as publicly denying fundamental articles of faith, or when a church’s doctrine and life are no longer under the control of the Word. Surely discerning whether a church is true or false takes wisdom. But if these marks are present, we ought to err on the side of charity, until being given a reason to believe otherwise.
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 Herman Bavinck. Reformed Dogmatics Vol. IV (Grand Rapids, MI: Baker Academic), 311.
 Ibid. 312.
 Heinrich Hoppe, Reformed Dogmatics (Grand Rapids, MI: Baker Book House), 671.
 Ibid., Reformed Dogmatics (Grand Rapids, MI: Baker Book House), 671.
 Louis Berkhof, Systematic Theology (Grand Rapids, MI: William B. Eerdmans Publishing Company), 577.