No true transformation can happen without miraculous grace. There is surely truth to this argument. Without the gospel, we are slaves to sin. We cannot conquer sin or master it; as long as we are unconverted, sin is in fact our master. We need God-given faith in Christ to know true and lasting transformation.
But I am wondering if, in highlighting this ultimate truth, we might forget a penultimate (secondary) reality. It is good and well to train children, pre-conversion, in obedience and self-control. If you do this in a way that indicates that successfully resisting a given temptation equates with the highest form of pleasing God, then that’s problematic. In other words, if you train kids that doing right actions saves them, that’s tragic. But it’s also tragic to not raise children to discern right from wrong and to think that they have no ability whatsoever to follow commands.
If, though, you train children in good habits while always holding out the need for repentance and faith, I think you’re being a wise and godly parent. The father who speaks repeatedly to his son in Proverbs clearly directs him to steer clear of sin. The father is forming habits in his son, and those habits are not opposed to saving faith. They are creating channels through which the life-giving water of the gospel will flow.
Christ is, of course, our ultimate motivation. The gospel is, correspondingly, the ultimate force in sanctification. But we should not make the mistake of thinking that obedience–even pre-conversion obedience–is antithetical to the gospel. It most surely is not. It seems to me that we are to follow the flow of Scripture in training our children. They learn the need to obey, the requirements of God’s holy standards, and we train them to do so (working from the Old Testament on up). But they quickly discover that they cannot ultimately fulfill the requirements upon them and must know Christ as savior if they are to be counted righteous before the holy judge (this is the miracle we discover in the New Testament). After their faith and repentance takes root, they are now empowered in an unprecedented way to obey and give glory to God. The Holy Spirit in us, through our union with Christ, provides a power and a motivation never before possible (this is what Paul and the apostles labored to help early Christians understand).
So: teach your young kids good habits. Teach them good manners. Train them in self-control. Model what being a Christian is like, and encourage them to follow your behavior. Instill in them that obedience is the cornerstone of being a child. Discipline them when they fail on this point. And consistently–though not mechanistically or fearfully–hold out their only true hope for life and faith, the message of free grace in Christ.
Your children will thank you after their conversion that you trained them in good habits, even as they will recognize that only the gospel truly sustains holy living.