After having this discussion with a friend just yesterday, I came across these wise words from Kevin DeYoung...
Error #1: The good we do can in some small way make us right with God. This is a denial of the gospel. The good we do is of no use to us in our justification because “even the very best we do in this life is imperfect and stained with sin” (HC Q/A 62). We “cannot do any work that is not defiled by our flesh and also worthy of punishment” (BC Art. 24).
Error #2: We must be good Christians so that God will keep loving us. To the contrary, the good news of justification by faith alone means that we can now “do a thing out of love for God” instead of “only out of love for [ourselves] and fear of being condemned” (BC Art. 24). In the midst of daily sins and weakness the struggling Christian should “flee for refuge to Christ crucified” (CD 5.2), truths that “it is not by their own merits or strength but by God’s undeserved mercy that they neither forfeit faith and grace nor remain in their downfalls to the end and are lost” (CD 5.8).
Error #3: If sanctification is a work of divine grace in our lives, then it must not involve our effort. We are absolutely “indebted to God for the good works we do” (BC Art. 24). He is the one at work in us both to will and to do according to his good pleasure. At the same time, “faith working through love” leads “a man to do by himself the works that God has commanded in his Word” (BC. Art. 24). Our ability to do good works “is not at all” in ourselves, but we still “ought to be diligent in stirring up the grace of God that is in [us]” (WCF 16.3).
Error #4: Warning people of judgment is law and has no part to play in preaching the gospel. Actually, “preaching the gospel” should both “open and close the kingdom of heaven.” The kingdom of heaven is opened by proclaiming to believers what God has done for us in Christ. The kingdom of heaven is closed by proclaiming “to unbelievers and hypocrites that, as long as they do not repent, the anger of God and eternal condemnation rest on them. God’s judgment, both in this life and in the life to come, is based on this gospel testimony” (HC Q/A 84).
Error #5: There is only one reason Christians should pursue sanctification and that’s because of our justification. The Heidelberg Catechism lists several reasons—motivations even—for doing good. “We do good because Christ by his Spirit is also renewing us to be like himself, so that in all our living we may show that we are thankful to God for all he has done for us, and so that he may be praised through us. And we do good so that we may be assured of our faith by its fruits, and so that by our godly living our neighbors may be won over to Christ” (HC Q/A 86).
Error #6: Since we cannot obey God’s commandments perfectly, we should not insist on obedience from ourselves or from others. While it is true that “in this life even the holiest have only a small beginning of this obedience,” that’s not the whole story. “Nevertheless, with all seriousness of purpose, they do begin to live according to all, not only some, of God’s commandments” (HC Q/A 114). Because we belong to Christ and our good works are “sanctified by his grace” (BC Art. 24), God “is pleased to accept and reward that which is sincere, although accompanied with many weaknesses and imperfections” (WCF 13.6).
Error #7: The Ten Commandments should be preached in order to remind us of our sin, but not so that believers may be stirred up to try to obey the commandments. The Heidelberg Catechism acknowledges that “no one in this life can obey the Ten Commandments perfectly,” but it still insists that “God wants them preached pointedly.” For two reason: “First, so that the longer we live the more we may come to know our sinfulness and the more eagerly look to Christ for forgiveness of sins and righteousness.” And “Second, so that, while praying to God for the grace of the Holy Spirit, we may never stop striving to be renewed more and more after God’s image, until after this life we reach our goal: perfection” (HC Q/A 115).
Error #8: Being fully justified as Christians, we should never fear displeasing God or offending him. The promise of divine preservation does not mean that true believers will never fall into serious sin (CD 5.4). Even believers can commit “monstrous sins” that “greatly offend God.” When we sin in such egregious ways, we “sometimes lose the awareness of grace for a time” until we repent and God’s fatherly face shines upon us again (5.5). God being for us in Christ in a legal and ultimate sense does not mean he will never frown upon our disobedience. But it does mean that God will always effectively renew us to repentance and bring us to “experience again the grace of reconciled God” (5.7).
Error #9: The only proper ground for assurance is in the promises of God found in the gospel. Assurance is not to be sought from private relation but from three sources: from faith in the promises of God, from the testimony of the Holy Spirit testifying to our spirits that we are children of God, and from “a serious and holy pursuit of a clear conscience and of good works” (CD 5.10). Assurance is not inimical to the pursuit of holiness, but intimately bound up with it. We walk in God’s ways “in order that by walking them [we] may maintain the assurance of [our] perseverance” (5.13). Personal holiness is not only a ground for assurance; the desire for assurance is itself a motivation unto holiness.
Error #10: Threats and exhortations belong to the terrors of the law and are not to be used as a motivation unto holiness. This is not the view of the Canons of Dort: “And, just as it has pleased God to begin this work of grace in us by the proclamation of the gospel, so he preserves, continues, and completes his work by the hearing and reading of the gospel, by meditation on it, by its exhortations, threats, and promises, and also by the use of the sacraments” (CD 5.14). Notice two things here. First, God causes us to persevere by several means. He makes promises to us, but he also threatens. He works by the hearing of the gospel and by the use of the sacraments. He has not bound himself to one method. Surely, this helps us make sense of the warnings in Hebrews and elsewhere in the New Testament. Threats and exhortations do not undermine perseverance; they help to complete it. Second, notice the broad way in which Dort understands the gospel (in this context). In being gospel-centered Christians, we meditate on the “exhortations, threats, and promises” of the gospel. In a strict sense we might say that the gospel is only the good news of how we can be saved. But in a wider sense, the gospel encompasses the whole story of salvation, which includes not only gospel promises but also the threats and exhortations inherent in the gospel.