Why we say amen

For no matter how many promises God has made, they are "Yes" in Christ. And so through him the "Amen" is spoken by us to the glory of God.2 Corinthians 1:20
The little word Amen indicates strong affirmation and means "Let it be so." It expresses the faith we should have when we pray. Christ said, "If you believe, you will receive whatever you ask for in prayer" (Matthew 21:22). He also said, "Whatever you ask for in prayer, believe that you have received it, and it will be yours" (Mark 11:24). The Samaritan woman received what she asked for because she didn't stop asking and firmly believed. In response, the Lord said to her, "You have great faith! Your request is granted" (Matthew 15:28). James also said, "But when he asks, he must believe and not doubt, because he who doubts is like a wave of the sea, blown and tossed by the wind" (James 1:6).

So as the author of Ecclesiastes said, "The end of a matter is better than its beginning" (Ecclesiastes 7:8). For at the end of your prayers, you say, "Amen," with heartfelt confidence and faith. When you say, "Amen," the prayer is sealed, and it certainly will be heard. Without this ending, neither the beginning nor the middle of the prayer will be of any benefit.