Q15: Since No One Can Keep the Law, What Is its Purpose?

New City Catechism: Question 15


Christians practice catechesis to instruct believers on the foundational truths of the Christian faith. In a question and answer format, this form of discipleship teaches the Apostle’s Creed, the Ten Commandments, the Lord’s Prayer, along with the basics of the Bible. The New City Catechism, created by Redeemer Presbyterian Church in New York City, asks 52 questions, one for each week of the year, on topics such as God, creation, and salvation. Each video provides an extended answer to the question from either a pastor at Redeemer or council members of the Gospel Coalition. This video with Ligon Duncan, Chancellor and CEO of Reformed Theological Seminary, answers the question, "Since no one can keep the law, what is its purpose?”


Romans 3:20 (ESV)

20For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin.

Scripture quotations marked (ESV) are from The Holy Bible, English Standard Version®, copyright © 2001 by Crossway Bibles, a publishing ministry of Good News Publishers. Used by permission. All rights reserved.



We can respond to question fifteen with the following answer: that we may know the holy nature and will of God, and the sinful nature and disobedience of our hearts; and thus our need of a Savior. The law also teaches and exhorts us to live a life worthy of our Savior.


Ligon said God’s Law helps us know Him, know ourselves, know our needs, and know a life of blessedness. What stands out to you the most about this answer? Why?
Log In to Continue


God’s Law serves as a window into God’s character. We can also see our sin and our need for a Savior. A life that perfectly observes God’s Law is a life full of blessing, so the Law opens our eyes to abundant life through following God.


Does the answer to this question impact your Christian walk? If so, how and why?
Log In to Continue

Read through Romans 3:20. Take a moment to reflect on the purpose of the Law. Use the space below to respond. You can write out a prayer, list the implications of the Law, or brainstorm ways you can apply the principle to your life.
Log In to Continue


The Catechism can help you remember the core beliefs of Christianity. Take time this week to learn the answer to this question and memorize Romans 3:20. Allow God to transform your heart, mind, and actions as you obey God.



 To learn more about New City Catechism or to download the app, click here