We use the Heidelberg Catechism in our worship. Sometimes we read it responsively. Other times I'll work it into my communion liturgy. I'll quote it in my sermons from time to time. I've seen the Catechism used effectively as Sunday school material.
God tells me that I need to provide for my family, discipline and teach my children, and love my wife as Christ loves the church. If I don't do that, I'm being unfaithful and sinful.
A catechism is simply a tool for teaching the fundamentals of the faith. Unlike a creed or confession, a catechism uses questions and answers. Many Protestant confessional traditions, like Lutherans, Presbyterians, and Reformed, have used catechisms for centuries. Initially, most catechisms were intended for children.
Sometimes Christians live in a terror of universal obligation: AIDS over here, people to be saved over here, a crushing sense of low-level guilt every day of our lives. Question to ask: Where has God put me right now? I need to say no to a whole bunch of other things because if I don't say no I can't say yes to others.
Much of the impotence of American churches is tied to a profound ignorance and apathy about justification. Our people live in a fog of guilt. Or just as bad, they think being a better person is all God requires.
Churches that should be talking about the work of Christ on the cross and the grace of God for sinners are stuck on recycled pop psychology, moral exhortation, or entertainment. But these fail to speak to the eternal question that haunts all of us: 'How do I know that I'm OK?' We all want to know we are justified.