"But another reason why so many divine acts are attributed to faith is, because other exercises are included in the description of faith, which though they always accompany it, ought not to be confounded with it. It was, two hundred years ago, a question much agitated among the divines of Holland, whether love entered into the essence of faith. And in our own country, faith and love have not been kept distinct. A very prevalent system of theology makes the essence of faith to be love. Much evil arises from confounding what are so clearly distinguished in the Word of God. If faith and love were identical, how could it be said that "faith works by love"? (Gal 5:6) The apostle Paul speaks of faith, hope, and love, as so distinct, that, although they are all necessary, they may be compared as to excellency—"The greatest of these is charity". (1 Cor 13:13) The celebrated Witsius, in his Economy of the Covenants, in describing faith, among the various acts which he attributes to this divine principle, reckons "love of the truth", (2 Thess 2:10) and "hungering and thirsting after Christ". (Matt 5:6) Now, it is an abuse of language to say that faith loves or desires; faith works by love, and excites hungering and thirsting desires after Christ.

But, it may be asked, if these graces are inseparably connected, why be so solicitous to distinguish them? First, because in so doing we follow the sacred writers; secondly, because it has a bad effect to use a Scriptural word to express what it was never designed to express; and, thirdly, because of the special office of faith in a sinner's justification; in which neither love nor any other grace has any part, although they are the effects of faith. When love is confounded with a justifying faith, it is very easy to slide into the opinion that as love is the substance of evangelical obedience, when we are said to be justified by faith, the meaning is, that we are justified by our own obedience. And accordingly, in a certain system of divinity valued by many, the matter is thus stated: faith is considered a comprehensive term for all evangelical obedience. The next step is—and it has already been taken by some—that our obedience is meritorious, and when its defects are purged by atoning blood it is sufficient to procure for us a title to eternal life. Thus have some, boasting of the name of Protestants, worked around, until they have fallen upon one of the most offensive tenets of Popery. But it would be difficult to bring a true penitent to entertain the opinion that his own works were meritorious, or could in the least recommend him to God. The whole of God's dealings with the souls of His own people effectually dispel from their minds every feeling of this kind. The very idea of claiming merit is most abhorrent to their feelings.

But while it is of importance to distinguish faith from every other grace, yet it is necessary to insist on the fact that that faith which does not produce love and other holy affections is not a genuine faith. In the apostles' days a set of libertines arose who boasted of their faith—but they performed no good works to evince the truth of their faith. Against such the apostle James writes, and proves that such a faith was no better than that of devils, and would justify no man; that the faith of Abraham and other believers, which did justify, was not a dead faith—but living; not a barren faith—but productive of good works, and proved itself to be genuine by the acts of duty which it induced the believer to perform."

(From, Thoughts on Religious Experience, 74-75)

Thanks to Gary Steward for this:

***

“The natural consequence of this assent, is the LOVE of the truth thus known and acknowledged. This is the third act of faith, and of this the Apostle speaks when he says; “They received not the love of the truth that they might be saved.” Since the saving truths of the Gospel afford a bright manifestation of the glory of God, as not only his veracity in his testimony, but also his wisdom, holiness, righteousness, goodness, power, and other divine perfections, shine forth in them,—the believing soul, contemplating these amiable perfections of the Deity in those truths, cannot fail to burn with an ardent love for them, to exult in them, and to glorify God…We admit that, strictly speaking, love is to be distinguished from faith; yet the workings of these two graces are so interwoven with each other, that we can neither explain nor exercise faith, without some operations of love intermingling, such as that of which we now treat. This remark has been formerly made by some of the greatest Divines; as, not to mention others at present, by Chamier and Wendelin. Each of these writers avails himself of the authority of Augustine, and makes the following quotation from him: “What is it to believe in God? It is by believing to love him.” See, also, Le Blanc, that celebrated Divine of Sedan, in his learned Theses. If any one, however, is disposed, agreeably to the language of the Schools, to denominate this love, an imperate act of faith, we shall not contend with him; provided it is understood that the believing soul, while exercising faith, cannot but sincerely love the doctrines of the Gospel, known and acknowledged, as they are in Jesus, rejoicing that such things are true, and delighting in the truth; and is thus very differently affected from devils and ungodly men, who disrelish those doctrines which they know to be true, and wish that they were false.” (Witsius, The Apostles’ Creed, 2 vols. 1:46-48).

Since the 1970s the Norman Shepherd and his followers have argued that faith justifies because is it not alone. They reject the notion that sanctity is nothing but the fruit of justification.

The funny thing is that Zacharias Ursinus, the primary author of the Heidelberg Catechism addressed this position explicitly. Thanks to Brad Lindvall for sending this.

***

Objection 4:

Faith does not justify without that which is required in those who are justified. Good works are required in those who are justified. Therefore, faith is not without good works, and so does not justify alone.

Answer:

There is here the same fallacy to which reference has just been made, on account of the doubtful construction of the particle without. Faith does not, indeed, justify without those things which are required in those who are justified. But although it never exists alone, and is always joined with love, by which it works, yet it alone justifies – is the act of embracing and applying to itself the merits of Christ. The minor also must be more fully explained; for faith and good works are not required in the same sense in those who are justified. Faith, with its own peculiar act, (without which it cannot be considered) is required as the necessary instrument, by which we apply to ourselves the merits of Christ. Good works, on the other hand, are not required that by them we may apprehend the merits of Christ, much less that we may be justified on account of them; but that we may thereby prove our faith, which without good works is dead, and can only be known by their presence. Good works are required as the fruits of our faith, and as the evidences of our gratitude to God. That is not always necessary for the accomplishment of a certain result, which is necessarily connected with the cause of the same thing. So good works, although they are necessarily connected with faith, are nevertheless not necessary for the apprehension of the merits of Christ. (Commentary on the Heidelberg Catechism, Q. 64, p. 337).

Olevianus, Beza, Perkins, Twisse, The Marrow Men: Lutherans? You decide.

***

Caspar Olevianus (1536-87). For this reason the distinction between law and Gospel is retained. The law does not promise freely, but under the condition that you keep it completely. And if someone should transgress it once, the law or legal covenant does not have the promise of the remission of sins. On the other hand, the Gospel promises freely the remission of sins and life, not if we keep the law, but for the sake of the Son of God, through faith (Ad Romanos Notae, 148; Geneva, 1579).

Theodore Beza (1534-1605). We divide this Word into two principal parts or kinds: the one is called the 'Law,' the other the 'Gospel.' For all the rest can be gathered under the one or other of these two headings...Ignorance of this distinction between Law and Gospel is one of the principal sources of the abuses which corrupted and still corrupt Christianity (The Christian Faith, 1558)

William Perkins (1558-1602). The basic principle in application is to know whether the passage is a statement of the law or of the gospel. For when the Word is preached, the law and the gospel operate differently. The law exposes the disease of sin, and as a side-effect, stimulates and stirs it up. But it provides no remedy for it. However the gospel not only teaches us what is to be done, it also has the power of the Holy Spirit joined to it....A statement of the law indicates the need for a perfect inherent righteousness, of eternal life given through the works of the law, of the sins which are contrary to the law and of the curse that is due them.... By contrast, a statement of the gospel speaks of Christ and his benefits, and of faith being fruitful in good works (The Art of Prophesying, 1592, repr. Banner of Truth Trust,1996, 54-55).

Marrow of Modern Divinity. Now, the law is a doctrine partly known by nature, teaching us that there is a God, and what God is, and what he requires us to do, binding all reasonable creatures to perfect obedience, both internal and external, promising the favour of God, and everlasting life to all those who yield perfect obedience thereunto, and denouncing the curse of God and everlasting damnation to all those who are not perfectly correspondent thereunto. But the gospel is a doctrine revealed from heaven by the Son of God, presently after the fall of mankind into sin and death, and afterwards manifested more clearly and fully to the patriarchs and prophets, to the evangelists and apostles, and by them spread abroad to others; wherein freedom from sin, from the curse of the law, the wrath of God, death, and hell, is freely promised for Christ's sake unto all who truly believe on his name (The Marrow of Modern Divinity; 1645, repr. 1978, 337-38. NB: The author of the Marrow was designated only as E.F. Therefore some scholars doubt whether Edward Fisher was actually the author).

William Twisse (1578-1646). How many ways does the Word of God teach us to come to the Kingdom of heaven? Two. Which are they? The Law and the Gospel. What says the Law? Do this and live. What says the Gospel? Believe in Jesus Christ and you shall be saved. Can we come to the Kingdom of God by the way of God's Law? No.Why so? Because we cannot do it. Why can we not do it? Because we are all born in sin. What is it to be none in sin? To be naturally prone to evil and ...that that which is good. How did it come to pass that we are all borne in sin? By reason of our first father Adam. Which way then do you hope to come tot he Kingdom of Heaven? By the Gospel? What is the Gospel? The glad tidings of salvation by Jesus Christ. To whom is the glad tidings brought: to the righteousness? No. Why so? For two reasons. What is the first? Because there is none that is righteous and sin not. What is the other reason? Because if we were righteous, i.e., without sin we should have no need of Christ Jesus. To whom then is this glad tiding brought? To sinners. What, to all sinners? To whom then? To such as believe and repent. This is the first lesson, to know the right way to the Kingdom of Heaven.: and this consists in knowing the difference between the Law and the Gospel. What does the Law require? That we should be without sin. What does the Gospel require? That we should confess our sins, amend our lives, and then through faith in Christ we shall be saved. The Law requires what? Perfect obedience. The Gospel what? Faith and true repentance. (A Brief Catechetical Exposition of Christian Doctrine, 1633).

The second witness is Zacharias Ursinus (1534-83, the primary author of the Heidelberg Catechism and the one authorized by Frederick III (who commissioned the catechism) to explain and defend it. 

***

Q.36 What distinguishes law and gospel? A: The law contains a covenant of nature begun by God with men in creation, that is, it is a natural sign to men, and it requires of us perfect obedience toward God. It promises eternal life to those keeping it, and threatens eternal punishment to those not keeping it. In fact, the gospel contains a covenant of grace, that is, one known not at all under nature. This covenant declares to us fulfillment of its righteousness in Christ, which the law requires, and our restoration through Christ's Spirit. To those who believe in him, it freely promises eternal life for Christ's sake (Larger Catechism, Q. 36).

Zacharias Ursinus (1534-83) on the organization of the Heidelberg Catechism. The chief and most important parts of the first principles of the doctrine of the church, as appears from the passage just quoted from the Epistle to the Hebrews, are repentance and faith in Christ, which we may regard as synonymous with the law and gospel. Hence, the catechism in its primary and most general sense, may be divided as the doctrine of the church, into the law and gospel. It does not differ from the doctrine of the church as it respects the subject and matter of which it treats, but only in the form and manner in which these things are presented, just as strong meat designed for adults, to which the doctrine of the church may be compared, does not differ in essence from the milk and meat prepared for children, to which the catechism is compared by Paul in the passage already referred to. These two parts are termed, by the great mass of men, the Decalogue and the Apostles' creed; because the Decalogue comprehends the substance of the law, and the Apostles' creed that of the gospel. Another distinction made by this same class of persons is that of the doctrine of faith and works, or the doctrine of those things which are to be believed and those which are to be done.

There are others who divide the catechism into these three parts; considering, in the first place, the doctrine respecting God, then the doctrine respecting his will, and lastly that respecting his works, which they distinguish as the works of creation, preservation, and redemption. But all these different parts are treated of either in the law or the gospel, or in both, so that this division may easily be reduced to the former.

There are others, again, who make the catechism consist of five different parts; the Decalogue, the Apostles' Creed, Baptism, the Lord's Supper, and Prayer; of which, the Decalogue was delivered immediately by God himself, whilst the other parts were delivered mediately, either through the manifestation of the Son of God in the flesh, as is true of the Lord's Prayer, Baptism, and the Eucharist, or through the ministry of the apostles, as is true of the Apostles' Creed. But all these different parts may also be reduced to the two general heads noticed in the first division. The Decalogue contains the substance of the law, the Apostles' Creed that of the gospel; the sacraments are parts of the gospel, and may, therefore, be embraced in it as far as they are seals of the grace which it promises, but as far as they are testimonies of our obedience to God, they have the nature of sacrifices and pertain to the law, whilst prayer, in like manner, may be referred to the law, being a part of the worship of God.

The catechism of which we shall speak in these lectures consists of three parts. The first treats of the misery of man, the second of his deliverance from this misery, and the third of gratitude, which division does not, in reality, differ from the above, because all the parts which are there specified are embraced in these three general heads. The Decalogue belongs to the first part, in as far as it is the mirror through which we are brought to see ourselves, and thus led to a knowledge of our sins and misery, and to the third part in as far as it is the rule of true thankfulness and of a Christian life. The Apostles' Creed is embraced in the second part inasmuch as it unfolds the way of deliverance from sins. The sacraments, belonging to the doctrine of faith and being the seals that are attached thereto, belong in like manner to this second part of the catechism, which treats of deliverance from the misery of man. And prayer, being the chief part of spiritual worship and of thankfulness, may, with great propriety, be referred to the third general part.

Zacharias Ursinus. In What Does The Law Differ From The Gospel? The exposition of this question is necessary for a variety of considerations, and especially that we may have a proper understanding of the law and the gospel, to which a knowledge of that in which they differ greatly contributes. According to the definition of the law, which says, that it promises rewards to those who render perfect obedience; and that it promises them freely, inasmuch as no obedience can be meritorious in the sight of God, it would seem that it does not differ from the gospel, which also promises eternal life freely. Yet notwithstanding this seeming agreement, there is a great difference between the law and the gospel. They differ, 1. As to the mode of revelation peculiar to each. The law is known naturally: the gospel was divinely revealed after the fall of man. 2. In matter or doctrine. The law declares the justice of God separately considered: the gospel declares it in connection with his mercy. The law teaches what we ought to be in order that we may be saved: the gospel teaches in addition to this, how we may become such as this law requires, viz: by faith in Christ. 3. In their conditions or promises. The law promises eternal life and all good things upon the condition of our own and perfect righteousness, and of obedience in us: the gospel promises the same blessings upon the condition that we exercise faith in Christ, by which we embrace the obedience which another, even Christ, has performed in our behalf; or the gospel teaches that we are justified freely by faith in Christ. With this faith is also connected, as by an indissoluble bond, the condition of new obedience. 4. In their effects. The law works wrath, and is the ministration of death: the gospel is the ministration of life and of the Spirit (Rom. 4:15, 2 Cor. 3:7) (Commentary on the Heidelberg Catechism, Q. 92).