Before commissioning the church with the task of evangelism (making disciples, baptizing, and teaching), Christ first gave these interesting (and assuring) words: “All authority in heaven and on earth has been given to me” (Mat. 28.18b). John Calvin comments quite helpfully:
Before relating that the office of teaching was committed to the disciples, Matthew says that Christ began by speaking of his power; and not without reason. For no ordinary authority would here have been enough, but sovereign and truly divine government ought to be possessed by him who commands them to promise eternal life in his [name] to reduce the whole world under his sway, and to publish a doctrine which subdues all pride, and lays prostrate the whole of the human race. And by this preface Christ not only encouraged the Apostles to full confidence in the discharge of their office, but confirmed the faith of his gospel in all ages. Never, certainly, would the Apostles have had sufficient confidence to undertake so arduous an office, if they had not known that their Protector sitteth in heaven, and that the highest authority is given to him; for without such a support it would have been impossible for them to make any progress. But when they learn that he to whom they owe their services is the Governor of heaven and earth, this alone was abundantly sufficient for preparing them to rise superior to all opposition. As regards the hearers, if the contemptible appearance of those who preach the gospel weakens or retards their faith, let them learn to raise their eyes to the Master himself, by whose power the majesty of the Gospel ought to be estimated, and then they will not venture to despise him when speaking by his ministers. – Calvin’s Commentaries: Harmony of the Evangelists.