Because Christians were "created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them" (Eph. 2:10), true believers in the Lord's promises have a desire to do what is right. This desire does not manifest itself in a hope that by doing good we can secure our place in heaven; rather, we desire to thank our Father for justifying us by grace alone through faith alone in Christ alone (vv. 8–9). Of course, since we Christians still struggle with the presence of sin, our understanding of right and wrong is not perfect. What seems like a good work to us may, in fact, not be good at all. Therefore, we need to understand what makes a work good and pleasing to God. The Heidelberg Catechism gives us this knowledge in question and answer 91.
According to the catechism, good works combine right motivation with right action. The necessity of right motivation is seen in that works are only good when they "are done out of true faith . . . for God's glory." Today's passage highlights the motivation of faith, the same faith that trusts Jesus for justification and perseveres in believing God's promises to the end of life. Doing good works requires us first to see that we have no righteousness in ourselves but that our Father declares us righteous and acceptable only when we rest in His Son (2 Cor. 5:21). We must believe that God exists and that He rewards those who seek Him appropriately, and the only way to seek our Creator properly is through Christ Jesus our Lord (Heb. 11:6; 12:1–2; see John 14:6).
First Corinthians 10:31 is one of the clearest texts in Scripture on the connection between good works and God's glory. The Apostle Paul tells us to do all things to the glory of God, a command drawn from the Bible's emphasis on the Lord's glory as His chief priority. God has revealed that filling the earth with His glory is His primary goal (Num. 14:21). He will not share this glory with any creature, so precious is it to Him (Isa. 42:8). It follows that His glory should be our chief end as well, and the highest good we can ever do is that which is directed toward His glory.
How do we know what actions bring Him glory? God's law tells us, for "the commandment is holy and righteous and good" (Rom. 7:12). As the Heidelberg Catechism teaches, good works conform to the Lord's commandments (A. 90).
We have a duty to do what is good, which means that we have a duty to do the right things for the right reasons. Although we should do right even when we are not motivated by faith and God's glory, we can hardly call a deed "good" in the sight of the Lord if we do not do it for the sake of His glory. We need to repent continually for our impure motivations and ask God to give us a strong desire to do all things unto His glory and praise.