For thine is the kingdom and the power and the glory forever and ever. Amen. What does this mean? This means that I should be certain that these petitions are pleasing to our Father in heaven, and are heard by Him; for He Himself has commanded us to pray in this way and has promised to hear us. Amen, amen, means, "yes, yes, it shall be so." (Small Catechism: The Lord's Prayer, Conclusion)
In the Name + of Jesus. Amen. Parents invented the word "maybe" so they don't have to commit. When you ask them for something or to do something, they can say "Maybe" which generally means "No, but I don't want to crush your hopes right away." Not so with our Lord! Here, at the end of the Lord's Prayer and all prayer we have this little word "Amen." "Amen" is from the Hebrew word for "True." When we say "Amen," we're confessing the words we've said are true and the promises of God that we base those words on are true.
Too often we pray like the kid in the movies. "Lord, I know you're up there, it's me. I know you're busy, but if you have time can you please do such and such?" To pray with an "Amen" is to pray in the Name of Christ and come boldly before God with our requests--especially the things we pray for in the Lord's Prayer we know the Lord must give us because He promised to give them. After all, He told us to ask for them!
So because Jesus died and took away our sins; because Jesus rose and defeated death; because Jesus shows us the Father's heart and enables us to call God "Father;" because of Christ and all that He has done for us, we cry out, "Do it, Lord! Make your name holy, your kingdom come, and your will be done! Give us what we need for our lives! Forgive our sins and teach us to forgive others! Keep temptation away from us and deliver us from evil and make us ready to die when the time comes! You said to ask for it. You promised to provide it! Amen! True! Yes!"
And the One who has washed you, absolved you, fed you with His Son's Body and Blood will do as He promised. It's all "Amen," yes in Jesus. In the Name + of Jesus. Amen.
Amen, that is, so shall it be, Make strong our faith in You, that we May doubt not but with trust believe That what we ask we shall receive. Thus in Your name and at Your Word We say, "Amen, O hear us, Lord!" (Our Father, Who from Heaven Above, LSB 766:9)