1] On this topic the adversaries quote against us: "If you would enter life, keep the commandments" (Matthew 19:17); likewise, "It is the doers of the law who will be justified" (Romans 2:13), and many other things about the Law and works. Before we reply to this, we must first declare what we believe about love and the fulfilling of the Law. I will put My Law within them, and I will write it on their hearts. (Jeremiah 31:33) Do we overthrow the law by this faith? By no means! On the contrary, we uphold the Law. (Romans 3:31) If you would enter life, keep the commandments. (Matthew 19:17) But [if I] have not love, I gain nothing. (1 Corinthians 13:3)
3] These and similar sentences testify that we are to keep the Law when we have been justified by faith, and so grow in fulfilling the Law more and more (by the Spirit). Furthermore, we are not talking about ceremonies, but about the Law that addresses the movements of the heart, namely the Ten Commandments. 4] Faith brings the Holy Spirit and produces a new life in hearts. It must also produce spiritual movements in hearts. The prophet Jeremiah shows what these movements are when he says, "I will put My law within them, and I will write it on their hearts" (Jeremoiah 31:33). Therefore, when we have been justified by faith and regenerated, we begin to fear and love God, to pray to Him, to expect aid from Him, to give thanks and praise Him, and to obey Him in times of suffering. We also begin to love our neighbors, because our hearts have spiritual and holy movements.
5] These things cannot happen until we have been justified through faith and regenerated (we receive the Holy Spirit). That's because the Law cannot be kept without Christ; likewise, the Law cannot be kept without the Holy Spirit. 6] But the Holy Spirit is received through faith, as Paul declares in Galatians 3:14, "that we might receive the promised Spirit through faith." 7] Also remember, how can the human heart love God while it knows that He is terribly angry and is oppressing us with earthly and endless distress? The Law always accuses us. It always shows that God is angry. 8] God is not loved until we receive mercy through faith. Not until then does He become someone we can love.
Condensed from CONCORDIA: THE LUTHERAN CONFESSIONS, copyright 2005,2006 by Concordia Publishing House. Used by permission. All rights reserved. To purchase a copy of CONCORDIA, call 800-325-3040.
Lord grant you faith in His grace alone for your salvation unto eternal life. Amen