A friend pointed out this man's post, and I think he has a great way of saying and summarizing things:
I'll post his 15 points here, though it's not the entirety of the post, but most of it.
So here it is: updated from the list in Show Them Jesus, 15 reasons why teaching kids first of all to believe God’s absolutely free grace in Jesus helps them to obey him.
1. Unless our hearts are in it, we aren’t fully obeying God. The great and first commandment is “’Love the Lord your God with all your heart’” (Matthew 22:37). So when our teaching helps kids to obey gladly, in a lifestyle of heartfelt gratitude rather than under pressure, we’re being very serious about God’s commands. We’re setting the bar high—where God sets it.
2. Unless good works spring from belief in Jesus, they aren’t even actually good. Belief is so central that “whatever does not proceed from faith is sin” (Romans 14:23) and, “without faith it is impossible to please him” (Hebrews 11:6). When our students learn about and believe the gracious blessings that are theirs in Jesus, they’ve laid the mandatory foundation for true obedience.
3. Obedience that’s grounded in love overcomes how we feel at the moment. Obeying out of love isn’t a wishy-washy thing that depends on feelings. There will be times our students don’t feel like obeying God at the moment. But if they love him they’ll have a steady, underlying desire to obey him, even amid temptation and mixed feelings. That’s the nature of love.
4. The worry that saved people might use grace as an excuse to sin has too small a view of salvation and grace. If we only taught how God freely forgives us—then okay, grace might make our students think they can sin as much as they like. But a gospel teacher helps kids to delight in a salvation that includes “a holy calling” (2 Timothy 1:9) and a hope laid up in heaven (Colossians 1:5). Kids gripped by such big grace have a taste of heaven and holiness that makes them hungry to live like holy, heaven-bound people now.
5. The idea that grace might let us get away with sin is not how reborn people should think. Romans 6:1–14 says an attitude that asks “How much can I get away with?” belongs to the old, worldly life. In Christ we’re set free of that selfish motive, so as teachers we shouldn’t pander to it by avoiding grace. The avoid-punishment motive does the minimum to get by, but a love-for-Christ motive does the most it can.
6. A strategy that starts with believing the gospel looks beyond surface sins to whole-self obedience. Unless our students address their root unbelief and coldness toward God, any fight against sin they undertake will have a lousy strategy. They’ll ignore the heart and get nowhere, because “out of the abundance of the heart his mouth speaks” (Luke 6:45).
7. We can’t do godly things consistently unless we have love for God. By willpower we might resist a sin here and there on a good day or when others are watching. But most of the time our hearts win out—we serve what we love. The only way our students become consistently obedient is by replacing sinful loves with a bigger love for God (1 John 2:15).
8. We can’t really obey God if we’re unsure of his pleasure toward us. If our students aren’t first convinced God loves them, forever and unfailingly, everything they do for him will only be a scheme to impress him and try to earn or keep his love. That’s manipulation, not obedience.
9. The grace we see in Jesus reveals God’s commands to be both urgent and beautiful. All his saving work and especially his sacrifice for sin increases our debt of love, compels us to be thankful, and shows us with unflinching starkness how evil and dangerous sin is and how pure the law and love of God are. We show kids Jesus not to soften anything, but to sharpen everything.
10. Unless we’re secure in Jesus we won’t dare face the full demands of God’s law. The best thing of all about Jesus and God’s law is that he kept it. Joined to him, we are eternally safe. Without this confidence, we inevitably reinterpret God’s rules into something less rigorous so that they seem manageable. Kids will always avoid certain demands of God unless they are confident enough in Christ to face them, unafraid of condemnation even though they know progress in fighting them might be painfully slow.
11. Knowing grace lets us get serious about God’s commands without falling into despair. When we fail to teach grace we have to be very careful to not push kids too hard to obey because they’ll easily get either discouraged or proud. But when students are already confident of God’s grace, then we can be much more forceful in urging them to obey. We have less worry that even hard teaching about obedience will lead to despair or self-righteousness.
12. Knowing grace makes us humble. Grace teaches us that all we have we owe to God. Grace-soaked kids become humble kids, and only humble people are happy to obey.
13. Knowing grace makes us confident. A life founded on how good we manage to be leads to feelings of guilt and weak self-image, but a life founded on being graciously joined to Jesus leads to the strongest possible self-image: that of being “in Christ.” Kids who have Christ as their self-image want to live like him—and confidently trust him to help them do it.
14. Knowing grace leads us to worship. Christian worship is a response to who Jesus is and all he’s done for us, and doing God’s will is an act of “spiritual worship” (Romans 12:1–2). Grace-filled kids don’t rejoice in their behavior as much as they rejoice in Jesus—and behave as an overflow of that worship.
15. God means for his kindness to motivate us to obey. In Romans, Paul directly addresses the possibility that some people might presume God’s forgiveness comes easily and therefore take their sin lightly. But he doesn’t say that the solution is to stop teaching grace. Instead, he explains that grace is designed to have the opposite effect: “Do you presume on the riches of his kindness and forbearance and patience, not knowing that God’s kindness is meant to lead you to repentance?” (Romans 2:4). God’s kindness, when properly understood, leads to repentance. Kids see how richly his love has reached down to them—with the compassion of the cross—and are compelled to hate sin like he does.