What follows is from Commentary on the Heidelberg Catechism, pages 484 and 485. It occurs in the context of the section entitled “Why Good Works Are to Be Done, or Why Are They Necessary.” Ursinus lists reasons under three headings: Why good works are to be done in relation to God, on our own account, and for the sake of our neighbor. In listing reasons why we should do good works on our own account, he includes, “that we may escape temporal and eternal punishment” (p. 484). Then he discusses the following question. To put Ursinus’ views in proper context I have included some statements from other Reformed writers.The question, whether good works are necessary to salvation, belongs properly to this place. There have been some who have maintained simply and positively, that good works are necessary to salvation, whilst others, again, have held that they are pernicious and injurious to salvation. Both forms of speech are ambiguous and inappropriate, especially the latter; because it seems not only to condemn confidence, but also the desire for performing good works. It is, therefore, to be rejected. The former expression must be explained in this way; that good works are necessary to salvation, not as a cause to an effect, or as if they merited a reward, but as a part of salvation itself, or as an antecedent to a consequent, or as a means without which we cannot obtain the end. In the same way we may also say, that good works are necessary to righteousness or justification, with which regeneration is inseparably connected. But yet we would prefer not to use these forms of speech, 1. Because they are ambiguous. 2. Because they breed contentions, and give our enemies room for caviling. 3. Because these expressions are not used in the Scriptures with which our forms of speech should conform as nearly as possible. We may more safely and correctly say, That good works are necessary in them that are justified and that are to be saved. To say that good works are necessary in them that are to be justified, is to speak ambiguously, because it may be so understood as if they were required before justification, and so become a cause of our justification. Augustine has correctly said: “Good works do not precede them that are to be justified, but follow them that are justified.” We may, therefore, easily return an answer to the following objection: That is necessary to salvation without which no one can be saved. But no one who is destitute of good works can be saved, as it is said in the 87th Question. Therefore, good works are necessary to salvation. We reply to the major proposition, by making the following distinction: That without which no one can be saved is necessary to salvation, viz: as a part of salvation, or as a certain antecedent necessary to salvation, in which sense we admit the conclusion; but not as a cause, or as a merit of salvation. We, therefore grant the conclusion of the major proposition if understood in the sense in which we have just explained it. For good works are necessary to salvation, or, to speak more properly, in them that are to be saved (for it is better thus to speak for the sake of avoiding ambiguity,) as a part of salvation itself; or, as an antecedent of salvation, but not as a cause of merit of salvation.
THIRD QUESTION: THE NECESSITY OF GOOD WORKS
Are good works necessary to salvation? We affirm.
II. There are three principal opinions about the necessity of good works…; The third is that of those who (holding the middle ground between these two extremes) neither simply deny, nor simply assert; yet they recognize a certain necessity for them against the Libertines, but uniformly reject the necessity of merit against the Romanists. This is the opinion of the orthodox.
III. Hence it is evident that the question here does not concern the necessity of merit, causality, and efficiency—whether good works are necessary to effect salvation or to acquire it by right. (For this belongs to another controversy, of which hereafter). Rather the question concerns the necessity of means, of presence and of connection or order—Are they required as the means and way for possessing salvation? This we hold.
IV. Although the proposition concerning the necessity of good works to salvation (which was thrust forward in a former century by the Romanists under the show of a reconciliation in the Intermistic formula, but really that imperceptibly the purity of the doctrine concerning justification might be corrupted) was rejected by various Lutheran theologians as less suitable and dangerous; nay, even by some of our theologians; still we think with others that it can be retained without danger if properly explained. We also hold that it should be pressed against the license of the Epicureans so that although works may be said to contribute nothing to the acquisition of our salvation, still they should be considered necessary to the obtainment of it, so that no one can be saved without them–that thus our religion may be freed from those most foul calumnies everywhere cast mot unjustly upon it by the Romanists (as if it were the mistress of impiety and the cushion of carnal licentiousness and security)…
VII. And as to the covenant, everyone knows that it consists of two parts: on the one hand the promise on the part of God; on the other the stipulation of obedience on the part of man… [emphasis added].
Does faith alone justify? We affirm against the Romanists.
III. But that the state of the question may be the more easily understood, we must remark that a twofold trial can be entered into by God with man: either by the law (inasmuch as he is viewed as guilty of violating the law by sin and thus comes under the accusation and condemnation of the law); or by the gospel (inasmuch as he is accused by Satan of having violated the gospel covenant and so is supposed to be an unbeliever and impenitent or a hypocrite, who has not testified by works the faith he has professed with his mouth). Now to this twofold trial a twofold justification ought to answer; not in the Romish sense, but in a very different sense. The first is that by which man is absolved from the guilt of sin on account of the righteousness of Christ imputed to us and apprehended by faith; the other is that by which he is freed from the charge of unbelief and hypocrisy and declared to be a true believer and child of God; one who has fulfilled the gospel covenant (if not perfectly as to degree, still sincerely as to parts) and answered to the divine call by the exercise of faith and piety. The first is justifica- tion properly so called; the other is only a declaration of it. That is justification of cause a priori; this is justification of sign or of effect a posteriori, declaratively. In that, faith alone can have a place because it alone apprehends the righteousness of Christ, by whose merit we are freed from the condemnation of the law; in this, works also are requited as the effects and signs of faith, by which its truth and sincerity are declared against the accusation of unbelief and hypocrisy. For as faith justifies a person, so works justify faith.
IV. The question does not concern justification a posteriori and declaratively in the fatherly and gospel trial-whether faith alone without works concurs to it (for we confess that works come in here with faith; yea, that works only are properly regarded because it is concerned with the justification of faith, which can be gathered from no other source more certainly than by works as its effects and indubitable proofs). Rather the question concerns justification a priori, which frees us from the legal trial, which is concerned with the justification of the wicked and the perfect righteousness, which can be opposed to the curse of the law and acquire for us a tight to life-whether works come into consideration here with faith (as the Romanists hold) or whether faith alone (as we maintain).
V. (2) The question is not whether faith alone justifies to the exclusion either of the grace of God or the righteousness of Christ or the word and sacraments ( by which the blessing of justification is presented and sealed to us on the part of God), which we maintain are necessarily required here; but only to the exclusion of every other virtue and habit on our part. Hence the Romanists have no reason for accusing us of confusion (akatastasias) in this argument as if we ascribed justification at one time to the grace of God, at another to the blood of Christ and then again to faith. For all these as they are mutually subordinated in a different class of cause, consist with each other in the highest degree.Robert Shaw
Good works are essentially prerequisite to an admission into heaven. Though they do not merit everlasting life, yet they are indispensably necessary in all who are “heirs of the grace of life.” Believers, “being made free from sin, have their fruit unto holiness, and the end everlasting life.”-Rom. vi. 22 [from his commentary on the Westminster Confession of Faith, chapter 16, "of good works"]A. A. Hodge
[Good works] are necessary to the attainment of salvation, not in any sense as a prerequisite to justification, nor in any stage of the believer’s progress meriting the divine favor, but as essential elements of that salvation, the consubstantial fruits and means of sanctification and glorification. A saved soul is a holy soul, and a holy soul is one whose faculties are all engaged in works of loving obedience. Grace in the heart cannot exist without good works as their consequent. Good works cannot exist without the increase of the graces which are exercised in them. Heaven could not exist except as a society of holy souls mutually obeying the law of love in all the good works that law requires. Eph. v. 25 — 27; 1 Thess. iv. 6, 7; Rev. xxi. 27. [from his commentary on the Westminster Confession of Faith, chapter 16, "of good works"]