“Christian virtue needs to grounded on the bedrock of grace. Education in virtue is no substitute for gospel. If all you’re offering your kids is a moral course of instruction, all you’re doing is bringing up Pharisees. You’re raising a household of moralistic prigs. You’re going to get two inches of snow on a dunghill: it looks really pretty, and it photographs well, but it is what it is. Or to use the illustration the great Puritan Thomas Watson once used, you’re treating a broken leg by putting a silk stocking on it. An external conformity to virtuous behavior is not going to cut it. Everything depends upon the new birth.”
Keep Your Kids, pp. 46-47