How reluctant men would be to plead that cause on a deathbed which they so stoutly stand up for with tongue and pen when at ease, and the evil day far away! They seem to be jealous lest God's grace and Christ's righteousness have too much room, and men's works too little, in the business of justification. But was there ever a sensible dying person exercised with this jealousy as to himself? ...
Consider how it is with the most holy and eminent saints when dying. Did you ever see or hear any boasting of their works and performances? They may and do own, to the praise of his grace, what they have been made to be, what they have been helped to do or suffer for Christ's sake. But when they draw near to the awful tribunal, what else is in their eye and heart but only free grace, ransoming blood, and a well-ordered covenant in Christ the surety? They cannot bear to hear any make mention to them of their holiness, their own grace and attainments.
In a word, the doctrine of conditions, qualifications and rectoral [pastoral] government, and the distribution of rewards and punishments according to the new law of grace, will make but an uneasy bed to a dying man's conscience ... Why should men contend for that in their life that they know they must renounce at their death? Or neglect that truth now that they must betake themselves to then? Why should a man build a house which he must leave in a storm, or be buried in its ruins?" (pp. 31-33).
This doctrine [of justification] is a spiritual mystery, and does not lie level with a natural understanding (1 Cor. 2:10, 14). Working for life a man naturally understands, but believing for life, he understands not. To mend the old man, he knows; but to put on the new man by faith is a riddle to him. The study of holiness, and endeavoring to square his life according to God's law, he knows a little of, though he can never do it; but to draw sanctification from Christ by faith, and to walk holily in and through the force of the Spirit of Christ in the heart by faith is mere empty language to him" (pp. 35-36).
Objection 2: But do not some abuse the grace of the gospel and turn it into wantonness? Answer: Yes, some do, ever did, and still will do so. But it is only the ill-understood and not believed doctrine of grace that they abuse. The grace itself, no man can abuse, for its power prevents its abuse. Let us see how Paul, that blessed herald of this grace ... deals with this objection (Rom. 6:1, etc.).
How does he prevent this abuse? Is it by extenuating what he had said (Rom. 5:20), that grace abounded much more where sin abounded? Is it by mincing grace smaller so that men may not choke upon it or have too much of it? Is it by mixing something of the law with it, to make it more wholesome? No, but only by plainly asserting the power and influence of this grace, wherever it really is, as he does at length in that chapter. This grace is all treasured up in Christ Jesus, offered to all men in the gospel, poured forth by our Lord in the working of faith, and drunk in by the elect in the exercise of faith. And it becomes in them a living spring, which will, and must, break out and spring up in all holy conversation" (p. 41).
Let us carefully keep the boundaries between the law and the gospel clear, which 'whosoever doth, is a right perfect divine', says blessed Luther, in his Commentary on the Epistle to the Galatians ... Let us keep the law as far from the business of justification as we would keep condemnation, its contrary. For the law and condemnation are inseparable, except by the intervention of Jesus Christ our surety (Gal. 3:10-14). But in the practice of holiness, the fulfilled law given by Jesus Christ to believers as a rule is of great and good use to them, as has been declared" (p. 62).
All the great fundamentals of Christian truth centre in this of justification. The Trinity of Persons in the Godhead; the incarnation of the only begotten of the Father; the satisfaction paid to the law and justice of God for the sins of the world by his obedience and sacrifice of himself in that flesh he assumed; and the divine authority of the Scriptures which reveal all this: these are all straight lines of truth that centre in this doctrine of justification of a sinner by the imputation and application of that satisfaction ...
Let not then zeal for so fundamental a point of truth as that of the justification of a sinner by faith in Christ be charged with folly ... Those that are for the righteousness of God by faith in Jesus Christ look upon it as the only foundation of all their hopes for eternity, and therefore they cannot but be zealous for it. And the contrary side are as hot for their own righteousness, the most admired and adored Diana of proud mankind, as if it were an image fallen down from Jupiter (pp. 68-70).
Excerpt, Justification Vindicated, by Robert Traill, Puritan Paperbacks (2002),