What good is it, my brothers, if a man claims to have faith but has no deeds? Can such faith save him? Suppose a brother or sister is without clothes and daily food. If one of you says to him, "Go, I wish you well; keep warm and well fed," but does nothing about his physical needs, what good is it? In the same way, faith by itself, if it is not accompanied by action, is dead. But someone will say, "You have faith; I have deeds." Show me your faith without deeds, and I will show you my faith by what I do.
--Epistle of James 2: 14-18
So the Christian who is consecrated by his faith does good works, but the works do not make him holier or more Christian, for that is the work of faith alone. And if a man were not first a believer and a Christian, all his works would amount to nothing and would be truly wicked and damnable sins.
--Martin Luther, The Freedom of a Christian
The following statements are therefore true: "Good works do not make a good man, but a good man does good works; evil works do not make a wicked man, but a wicked man does evil works." Consequently it is always necessary that the substance or person himself be good before there can be any good works, and that good works follow and proceed from the good person, as Christ also says, "A good tree cannot bear evil fruit, nor can a bad tree bear good fruit" [Matt. 7:18]. It is clear that the fruits do not bear the tree and that the tree does not grow on the fruits, also that, on the contrary, the trees bear the fruits and the fruits grow on the trees. As it is necessary, therefore, that the trees exist before their fruits and the fruits do not make trees either good or bad, but rather as the trees are, so are the fruits they bear; so a man must first be good or wicked before he does a good or wicked work, and his works do not make him good or wicked, but he himself makes his works either good or wicked.
--Martin Luther, Works 31:360-361
When God rewards my labors, He's merely crowning the works of His hands in my life."
If anyone says that the righteousness received is not preserved and also not increased before God by good works, but that those works are merely the fruits and signs of justification obtained, but not a cause of its increase, let him be anathema."
--Council of Trent, 1563
St. Thomas Aquinas' Summa Theologica:
Can man without grace and by his own natural powers fulfil the commandments of the Law?
Objection 1. It would seem that man without grace, and by his own natural powers, can fulfil the commandments of the Law. For the Apostle says (Rm. 2:14) that "the Gentiles who have not the law, do by nature those things that are of the Law." Now what a man does naturally he can do of himself without grace. Hence a man can fulfil the commandments of the Law without grace.
Objection 2. Further, Jerome says that "they are anathema who say God has laid impossibilities upon man." Now what a man cannot fulfil by himself is impossible to him. Therefore a man can fulfil all the commandments of himself.
Objection 3. Further, of all the commandments of the Law, the greatest is this, "Thou shalt love the Lord thy God with thy whole heart" (Mt. 27:37). Now man with his natural endowments can fulfil this command by loving God above all things, as stated above (3). Therefore man can fulfil all the commandments of the Law without grace.
On the contrary, Augustine says (De Haeres. lxxxviii) that it is part of the Pelagian heresy that "they believe that without grace man can fulfil all the Divine commandments."
I answer that, There are two ways of fulfilling the commandments of the Law. The first regards the substance of the works, as when a man does works of justice, fortitude, and of other virtues. And in this way man in the state of perfect nature could fulfil all the commandments of the Law; otherwise he would have been unable to sin in that state, since to sin is nothing else than to transgress the Divine commandments. But in the state of corrupted nature man cannot fulfil all the Divine commandments without healing grace. Secondly, the commandments of the law can be fulfilled, not merely as regards the substance of the act, but also as regards the mode of acting, i.e. their being done out of charity. And in this way, neither in the state of perfect nature, nor in the state of corrupt nature can man fulfil the commandments of the law without grace. Hence, Augustine (De Corrupt. et Grat. ii) having stated that "without grace men can do no good whatever," adds: "Not only do they know by its light what to do, but by its help they do lovingly what they know." Beyond this, in both states they need the help of God's motion in order to fulfil the commandments, as stated above (2,3).
Reply to Objection 1. As Augustine says (De Spir. et Lit. xxvii), "do not be disturbed at his saying that they do by nature those things that are of the Law; for the Spirit of grace works this, in order to restore in us the image of God, after which we were naturally made."
Reply to Objection 2. What we can do with the Divine assistance is not altogether impossible to us; according to the Philosopher (Ethic. iii, 3): "What we can do through our friends, we can do, in some sense, by ourselves." Hence Jerome concedes that "our will is in such a way free that we must confess we still require God's help."
Reply to Objection 3. Man cannot, with his purely natural endowments, fulfil the precept of the love of God, as stated above (3).
Whether man can merit everlasting life without grace?
Objection 1. It would seem that man can merit everlasting life without grace. For Our Lord says (Mt. 19:17): "If thou wilt enter into life, keep the commandments"; from which it would seem that to enter into everlasting life rests with man's will. But what rests with our will, we can do of ourselves. Hence it seems that man can merit everlasting life of himself.
Objection 2. Further, eternal life is the wage of reward bestowed by God on men, according to Mt. 5:12: "Your reward is very great in heaven." But wage or reward is meted by God to everyone according to his works, according to Ps. 61:12: "Thou wilt render to every man according to his works." Hence, since man is master of his works, it seems that it is within his power to reach everlasting life.
Objection 3. Further, everlasting life is the last end of human life. Now every natural thing by its natural endowments can attain its end. Much more, therefore, may man attain to life everlasting by his natural endowments, without grace.
On the contrary, The Apostle says (Rm. 6:23): "The grace of God is life everlasting." And as a gloss says, this is said "that we may understand that God, of His own mercy, leads us to everlasting life."
I answer that, Acts conducing to an end must be proportioned to the end. But no act exceeds the proportion of its active principle; and hence we see in natural things, that nothing can by its operation bring about an effect which exceeds its active force, but only such as is proportionate to its power. Now everlasting life is an end exceeding the proportion of human nature, as is clear from what we have said above (5, 5). Hence man, by his natural endowments, cannot produce meritorious works proportionate to everlasting life; and for this a higher force is needed, viz. the force of grace. And thus without grace man cannot merit everlasting life; yet he can perform works conducing to a good which is natural to man, as "to toil in the fields, to drink, to eat, or to have friends," and the like, as Augustine says in his third Reply to the Pelagians.
Reply to Objection 1. Man, by his will, does works meritorious of everlasting life; but as Augustine says, in the same book, for this it is necessary that the will of man should be prepared with grace by God.
Reply to Objection 2. As the gloss upon Rm. 6:23, "The grace of God is life everlasting," says, "It is certain that everlasting life is meter to good works; but the works to which it is meted, belong to God's grace." And it has been said (4), that to fulfil the commandments of the Law, in their due way, whereby their fulfilment may be meritorious, requires grace.
Reply to Objection 3. This objection has to do with the natural end of man. Now human nature, since it is nobler, can be raised by the help of grace to a higher end, which lower natures can nowise reach; even as a man who can recover his health by the help of medicines is better disposed to health than one who can nowise recover it, as the Philosopher observes (De Coelo ii, 12).