I must take it for granted that a minister, who sincerely desires, and who is likely to do good by his preaching, is such a one both in heart and in life, as St. Paul describes, 2 Tim. 1:13,14. "Who holds fast the form of sound words (or the pure apostolic doctrine) which he has heard, in faith and love which is in Christ Jesus; and who keeps that good thing which has been committed to him by the Holy Ghost which dwelleth in him."
It will not a little subserve the good ends proposed in the question, for a minister, very frequently, to lay in his sermons the distinguishing marks and characters both of the converted and of the unconverted, and that with all possible plainness, that so every one of his hearers may be able to judge of his own state, and may know to which of these two classes he belongs....
3. Distinguish between mere morality and true religion.
For this purpose also let a minister carefully and clearly distinguish in his preaching, betwixt mere morality and true religion; betwixt the moral honest man and the sound believer, who, from a deep conviction of the depravity of his nature and the errors of his life, has learned to hate sin from his heart, and lives by the faith of the Son of God....
And, because this kind of self-deceit is so very common, it is highly necessary for a minister to instruct his hearers with all possible plainness in the duty of self examination, and very often to exhort them to it; as more especially to inquire, if ever they were awakened from their natural sleep in sin? If they have escaped out of the snare of the devil? If ever they have had a lively and affecting sense of the corruption of their own hearts, and of the misery of their natural state? And, in short, whether they have good and solid reasons to conclude that they are regenerate persons? Whether they can find in themselves the genuine marks of a true conversion to God, and a living faith in Christ?...
It would also be of very considerable use for a minister often to explain, and to show the difference betwixt a legal and an evangelical frame and principle of religion; or betwixt that slavish fear, by which alone it is that some persons, even of a serious turn of mind, are forced and dragged as it were to their duty, and that evangelical newness of spirit, that filial love to God and delight in his service, which usually grows and flourishes in the soul where it is once planted, and which produces a free, unconstrained, and acceptable religion.
It would further be useful, and it is highly necessary, that ministers should not only preach up the necessity of conversion, and instruct their hearers to depend on the grace of Christ for it, but also that they should, very frequently, in their sermons explain the nature and the whole progress of conversion, sometimes more largely and distinctly, and at other times more briefly, endeavoring thereby to lead their hearers into a true knowledge of the state of their souls; and showing them how they must repent of their sins, what they must do to be saved from their natural misery and ruin, and, in short, how they may obtain the full salvation of the gospel; that so every one may be able to give an answer to that most important question, “What must I do that I may be a child of God and inherit eternal life?"
It might probably make some good impressions on the minds of the people, were a minister pretty often to inculcate, with great plainness and seriousness, the necessity of prayer; and more particularly what need they have to pray very earnestly to the God of grace that he would set home his word upon their hearts. that he would bring the good deed to perfection in their full and blessed conformity to himself. And further, so great is the ignorance of many persons concerning the duty of prayer, that they seem to have no other notion of it than merely a leading some forms out of a prayer-book. This makes it to be as necessary, as it would properly be a useful thing for a minister to lead them, as it were, by the hand, into this path of duty: that is, to explain it to them in a most easy and familiar manner, to show them that it requires no great art and skill to pray acceptably unto God....
It is further extremely necessary that ministers should very often take occasion to explain in their sermons that renewing or change of the mind, which is so essential to all true religion, and which yet, alas! but very few persons seem to understand, or indeed to have almost any notion of. Nor is it enough to explain that first and mighty change, which is at once made in a sinner at his conversion, when he comes to love that good which before he hated, and to hate that evil which he before loved; when from being an unbeliever he becomes a believer; or when his false and dead faith is changed into a true and saving one; but that further progressive change should also be much recommended, in which the Christian must be improving to the very end of his life, which St. Paul refers to, 2 Cor. iii. 18.
It is of considerable moment also that the whole faith and duty of a Christian be represented in its most amiable and attractive light, that so sinners may be won to religion upon a full conviction, that if they would do well for themselves and obtain true peace and comfort, the shortest, the surest, and indeed the only way is to turn in good earnest from sin to God and holiness; and that religion is by no means a grievous and melancholy thing, which any may need be afraid of, but full of pleasure and greatly desirable even for its own sake: and though it calls us, indeed, to a present combat, and requires us to fight and strive against sin; yet this is but in order to peace and to a certain victory, which will much more than recompense the toils of the war.
It were much to be wished that ministers would not take up more of their sermons than needs must in explaining their text, but rather, after as short an explication of it as is sufficient to lead their hearers into the true sense and meaning, (which must by no means be neglected,) hasten to the application; and in that, let a minister address himself to his hearers with a becoming seriousness and earnestness; let him apply his subject both to saints and sinners, to the converted and to the unconverted, in order to awaken the secure and careless, and to build up true believers in their faith and holiness. Experience would soon show that this is by far the more profitable way, than to spend almost the whole discourse, as some do, in explaining the text and subject, and then close with a very short application, because the time is gone.
It were also greatly to be wished, that those under-shepherds of the flock of Christ would make it more designedly and zealously the purpose of their preaching to bring sinners to him, who is the great Shepherd of the sheep; that they would strive by the most winning arguments they can possibly use, and especially by such as the grace of the gospel will naturally suggest, to persuade and even to compel them to come to him. As the hen when she lights on a few crumbs or grains of corn; how earnestly does she invite her brood to come and share the treasure with her! She will by no means be satisfied or leave off calling them till they come. Thus did our blessed Saviour....
For this purpose it is further requisite that a minister should very often take occasion to display, in the most lively colors that he can, the excellency and glory of Christ's person, the kindness of his heart, and the exceeding riches of his grace, both as he is God and man, as he is now a glorious triumphant Saviour, as well as once he sustained and executed the same office in a humbled and suffering state. And that he further inform his hearers what excellent blessings are treasured up in Christ to be bestowed on all his friends and people, that so they may be drawn to him by a principle of desire and love....
The love of Christ ought to be much more insisted on by preachers than what is commonly done; because when we apply to ourselves in a right manner his passion, death, and atonement, his merits, and that purchase of salvation which he hath made for us, the knowledge of his love to us, and of our pardon and justification through faith in his blood, is the truest spring and most powerful attractive of our love to him. Now the more we love Christ, and that for this very reason, because he first loved us, the better will every other branch of our religion flourish, every other grace and every duty will then flow from its proper fountain; and therefore the more a minister endeavors to instill this principle of sacred love into the hearts of his hearers, the more comfortable success will he probably see of his labors, in their spiritual improvement and growing obedience to the gospel.
I reckon also the duties of self-denial and weanedness from the world and its carnal pleasures, and, in short, from all the present things of sense and time, to be among those more important and necessary subjects which ministers should often preach upon, oftener indeed than most of them do. These are subjects which our Saviour Christ, when he was a preacher upon earth, very much insisted upon in his sermons....
Though the diligent reading of the scriptures themselves, even the inspired writings of the prophets and apostles, and the very words of our Saviour Christ, should be chiefly recommended, as they are undoubtedly far preferable to any other books of mere human composure; yet besides these, a minister may very profitably recommend to his hearers some other good books of religion, both ancient and modern, to be read by them at home in their own closets or families; such books, I mean, as are written in a truly evangelical strain, and with a spirit of lively devotion and piety....
Once more, let faithful ministers by no means forget to recommend it to their hearers, that they would familiarly acquaint themselves and converse with serious, lively, and growing Christians, and with such more especially as excel in the gift and spirit of prayer; for as a live coal kindles another that is cold and dead, so will the savory discourse, the fervent prayers, and the holy conversation of warm and lively Christians, be a probable means of kindling the same fire of divine love in the souls of dead sinners; or at least of nourishing and improving the sacred flame in the hearts of their more intimate Christian friends. Ministers should therefore do all they can to promote such Christian conversation amongst the more serious part of their hearers....
August Francke, The Most Useful Way of Preaching