Good works are only those works that God has commanded in his holy Word (Mic 6:8; Heb 13:21). Works that do not have this warrant are invented by people out of blind zeal or on a pretense of good intentions and are not truly good (Mt 15:9; Isa 29:13).
These good works, done in obedience to God’s commandments, are the fruit and evidence of a true and living faith (Jas 2:18, 22). Through good works believers express their thankfulness (Ps 116:12-13), strengthen their assurance (1Jn 2:3, 5; 2Pe 1:5-11), build up their brothers and sisters, adorn the profession of the gospel (Mt 5:16), stop the mouths of opponents, and glorify God (1Ti 6:1; 1Pe 2:15; Php 1:11). Believers are God’s workmanship, created in Christ Jesus for good works (Eph 2:10), so that they bear fruit leading to holiness and have the outcome, eternal life (Ro 6:22).
Their ability to do good works does not arise at all from themselves but entirely from the Spirit of Christ (Jn 15:4-5). To enable them to do good works, they need—in addition to the graces they have already received—an actual influence of the same Holy Spirit to work in them to will and to do his good pleasure (2Co 3:5; Php 2:13). Yet this is no reason for them to grow negligent, as if they were not required to perform any duty without a special motion of the Spirit. Instead, they should be diligent to stir up the grace of God that is in them (Php 2:12; Heb 6:11-12; Isa 64:7).
Those who attain the greatest heights of obedience possible in this life are far from being able to merit reward by going beyond duty or to do more than God requires. Instead, they fall short of much that is their duty to do (Job 9:2-3; Gal 5:17; Lk 17:10).
We cannot, even by our best works, merit pardon of sin or eternal life from God’s hand, due to the huge disproportion between our works and the glory to come, and the infinite distance between us and God. By these works we can neither benefit God nor satisfy him for the debt of our former sins (Ro 3:20; 4:6; Eph 2:8-9). When we have done all we can, we have only done our duty and are unprofitable servants. Since our good works are good, they must proceed from his Spirit (Gal 5:22-23); and since they are performed by us, they are defiled and mixed with so much weakness and imperfection that they cannot withstand the severity of God’s punishment (Isa 64:6; Ps 143:2).
Nevertheless, believers are accepted through Christ, and thus their good works are also accepted in him (Eph 1:6; 1Pe 2:5). This acceptance does not mean our good works are completely blameless and irreproachable in God’s sight. Instead, God views them in his Son, and so he is pleased to accept and reward that which is sincere, even though it is accompanied by many weaknesses and imperfections (Mt 25:21, 23; Heb 6:10).
Works done by unregenerate people may in themselves be commanded by God and useful to themselves and others (2Ki 10:30; 1Ki 21:27, 29). Yet they do not come from a heart purified by faith (Ge 4:5; Heb 11:4, 6) and are not done in a right manner according to the Word (1Co 13:1) nor with a right goal—the glory of God (Mt 6:2, 5). Therefore, they are sinful and cannot please God. They cannot qualify anyone to receive grace from God (Am 5:21-22; Ro 9:16; Tit 3:5), and yet their neglect is even more sinful and displeasing to God (Job 21:14-15; Mt 25:41-43).