In evangelical Christianity, to some degree after the so-called First Great Awakening and certainly after the so-called Second Great Awakening, the line between lay witness and the official (done from a particular ecclesiastical office) of preaching became blurred. The Reformed theologians who composed and edited the Heidelberg Catechism (1563) and the churches who adopted it did not blur this line. They certainly expected believers to talk to others about the faith (objective) and about their own, personal appropriation of Christ and his gospel through faith alone (subjective) but the left the preaching of the holy gospel to the church and particularly to the office of minister:

84. How is the Kingdom of Heaven opened and shut by the preaching of the Holy Gospel.

In this way: that according to the command of Christ, it is proclaimed and openly witnessed to believers, one and all, that as often as they accept with true faith the promise of the Gospel, all their sins are really forgiven them of God for the sake of Christ’s merits; and on the contrary, to all unbelievers and hypocrites, that the wrath of God and eternal condemnation abide on them so long as they are not converted. According to this testimony of the Gospel, God will judge men both in this life and in that which is to come (Heidelberg Catechism).

As inefficient as it may seem to us, God the Spirit has left to the office of preacher the ministry of announcing the good news and it through that act, announcing the incarnation, obedience, righteousness, death, resurrection, ascension, and return of Christ that he has promised to bring all of his elect to new life, to faith, and through faith alone to justification and salvation.

Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending you.” And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you withhold forgiveness from any, it is withheld.” (John 20:21–23; ESV).

The pronoun “them” refers to the disciples mentioned in v. 20. The resurrected Christ showed his hands to the disciples. He commissioned the disciples. To them he gave the authority to “forgive sins” and to withhold the same. In Romans 10 the Apostle Paul says that it is only through the hearing of the gospel that God’s people are brought to faith and saved and that hearing come through preaching and preaching comes from being sent:

How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent? As it is written, “How beautiful are the feet of those who preach the good news!” But they have not all obeyed the gospel. For Isaiah says, “Lord, who has believed what he has heard from us?” So faith comes from hearing, and hearing through the word of Christ (Rom 10:14–17; ESV).

Remarkably, there is little clear evidence for what is often called “every-member ministry” or even lay evangelism in the New Testament. I think a case can be made from John 9 for lay witness but there is abundant biblical evidence that the officers whom God has called are commissioned to announce the good news everywhere:

And we are witnesses of all that he did both in the country of the Jews and in Jerusalem. They put him to death by hanging him on a tree, but God raised him on the third day and made him to appear, not to all the people but to us who had been chosen by God as witnesses, who ate and drank with him after he rose from the dead. And he commanded us to preach to the people and to testify that he is the one appointed by God to be judge of the living and the dead. To him all the prophets bear witness that everyone who believes in him receives forgiveness of sins through his name.” (Acts 10:41–43; ESV).

Notice Peter’s appeal to his status as an authorized messenger: “but to us who had been chosen by God as witnesses.” This aspect of the NT mission is often overlooked in favor of what is essentially an assumption about what must be the case but we should be careful not to read our modern egalitarian assumptions back into the NT.

Nevertheless, God is calling his people and he is doing so through the preaching of the gospel. He is sending ministers and this external call (vocation) is the first key of the Kingdom of God. God the Spirit is exercising his effective or efficacious call through the public preaching of two words: the law and the gospel. Notice how the catechism structures and characterizes the preaching of the holy gospel: “the promise of the gospel” of free justification by grace alone, through faith alone (for which we use the verb “to accept”) on the ground of the imputation of Christ’s merits and it’s “contrary:” the condemnation of all those who do not believe this message.

This twofold gospel was reflected in the Heidelberg liturgy of 1563. There was a declaration of pardon and also an announcement of God’s eternal and relentless judgment against those, as we say, “who are not converted.” This is what we understand to be the “whole counsel” of God. It may seem counter-intuitive to us that God the Spirit should choose to use what Paul calls the “foolishness” of preaching (1 Cor 1:25) but that is exactly what he has done. This is because they kingdom is not brought by our efforts but by the sovereign power of God’s Spirit working through the due use of ordinary means.

Because of our modern history of “awakenings” we have been conditioned to neglect the ordained and the routine in favor of the unordained and the extraordinary. So, it can be difficult to re-think things, since it is not only counter-intuitive but it is contrary to the way we’ve been taught to think and what we’ve been conditioned to expect. Nevertheless, there it is. Week by week a minister is meant to enter the pulpit and announce these two aspects of the gospel, these two words. He does so with much prayer, fear, and trembling but with the expectation that God the Spirit is quietly, mysteriously working through the announcement of these words. As we look back over the history of redemption and the history of the church we can see that it has been so, even if, as we look about us now, it might seem quite hidden. One day it will all be made very clear what the Spirit has been doing (John 3).

Here are all the posts on the Heidelberg Catechism.