There are a couple of expressions that we use, in prayer, almost without thinking. One of them is the word “Amen.” This little term is more important than we might think. In at least one place in Scripture it is used as a substitute for truth. God is described as the “God of Amen” (Isa 65:16), which is translated in the ESV as the “God of Truth.” It was used in the ratification of a covenant in Jeremiah 11:5: “‘You shall say to them, Thus says Yahweh, the God of Israel: Cursed be the man who does not hear the words of this covenant that I commanded your fathers when I brought them out of the land of Egypt, from the iron furnace, saying, Listen to my voice, and do all that I command you. So shall you be my people, and I will be your God, that I may confirm the oath that I swore to your fathers, to give them a land flowing with milk and honey, as at this day.’ Then I answered, ‘Amen, Yahweh'” (Jer 11:3–5). It is used this way in Revelation 22:20. We use it most frequently as an affirmation after the doxology attached to the Lord’s Prayer. It is used this way in Psalm 72:19 “Blessed be his glorious name forever; may the whole earth be filled with his glory! Amen and Amen!” (ESV). Paul uses it at the end of his doxology in Romans 9:5. It is used as a liturgical response in 1 Cor 14:16. 1
It is in light of these uses that we confess:
129. What is the meaning of the word “Amen”?
Amen means: So shall it truly and surely be, for my prayer is much more certainly heard of God than I feel in my heart that I desire things of Him (Heidelberg Catechism).
When we say “amen” at the end of our prayers it is not merely a signal that we are done praying. It is a heartfelt affirmation of all that God has promised to us in the gospel, which we receive through faith alone (sola fide). To say the word amen is a confession of faith. When we say it, in faith, we are affirming that God will do what he has promised.
When we say amen in faith we are saying that God’s objective promises are true despite my subjective experience and condition. Witsius wrote:
By this word we express our sincere acknowledgments of the kingdom, power, and glory of God; our earnest desire to obtain from God such valuable blessings; and our faith resting on the promises of God, “the confidence that we have in him that if we ask any thing according to his will, he heareth us.” Luther, with his wonted liveliness of manner, wrote to Melancthon in the following terms:—“I pray for you, I have prayed, and I will pray, and I have no doubt I shall be heard, for I feel the AMEN in my heart.
It is fitting that the catechism comes to a close by emphasizing the objective reality of our justification and salvation by grace alone (sola gratia) and the subjective appropriation of that truth in our own hearts, since that is where the catechism began. Our subjective comfort is grounded in the objective reality accomplished for us, which we receive through faith alone (sola fide). It is out of the reality that God has graciously saved us and is graciously sanctifying us that we live the Christian life.
1. This summary relies upon Allen C. Myers, The Eerdmans Bible Dictionary (Grand Rapids: Eerdmans, 1987), s.v. “Amen.”
2. Herman Witsius, Sacred Dissertations on the Lord’s Prayer, trans. William Pringle (Edinburgh: Thomas Clark, 1839), 382.