Unless you’ve gone to a Roman Catholic mass recently, you may not realize that Roman Catholics do not say “For Thine is the Kingdom, and the Power, and the Glory, forever and ever” at the end of the Lord’s Prayer. And if you look up where Jesus gives the Lord’s Prayer to His disciples in Matthew and in Luke, you’ll notice that Jesus doesn’t say it either. So why do Lutherans? 
This week we confessed the Conclusion to the Lord’s Prayer:
What is the conclusion of the Lord’s Prayer?
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.”
It’s notable that Luther didn’t include this conclusion in his original drafts of the Small Catechism either. Like the Roman Catholic recitation of the prayer, Luther’s catechism ended with “Deliver us from evil.”
The phrase actually comes from an ancient Christian document called “The Didache” (DIDa-Kay). The word “didache” literally means “teaching”, and it was a manual on how to live a Christian life, including instructions on how to Baptize, administer Holy Communion, pray, and worship.
This Didache and many of the Greek translations of the Bible contained this conclusion, and so it was tacked on to the end of the prayer, as was the Hebrew word “Amen”. It was a common Jewish practice to end prayers with a blessing or doxology (statement of glory), and so the practice stuck.
The Roman Catholic translator Jerome, however, did not trust the Greek translations that added the conclusion, and so left it out of the Latin Gospel texts of Matthew (it rarely showed up in the Greek translations of Luke) when he was translating the Bible into Latin. Because of that, it never became a popular way to end the prayer in Latin and in the Roman Catholic church.
So, “what does this mean”? I don’t think that this practice is without meaning for us, a church body that loudly proclaims that “Sola Scriptura/Scripture Alone” is our guide. There are far too many Lutherans who have no clue what the text of the New Testament actually says when it records Jesus giving the Lord’s Prayer to the disciples. We may have the confession/absolution formulas or the “Glory to God” song memorized, but how well do we really know Scripture? Do we know Scripture well enough to distinguish it from liturgy?
Much of our liturgy is pulled from Scripture, or at least alludes to it. The confession/absolution includes bits of I John, the Greeting comes from 2 Corinthians, the Kyrie comes from Psalm 123, the Gospel verse contains a line from John 6, the written prayers in the bulletin before the “other intercessions” from the connection cards allude to the 4 readings for that Sunday, and much much more. But we miss out on those things if we’re not reading Scripture and comparing it with our liturgy.
I don’t think there’s anything “wrong” with having liturgy and liturgical things that don’t quote Scripture directly, but I think we need to balance that with a healthy personal reading of Scripture. If you know liturgy better than Scripture, then maybe it’s time to learn more Scripture. Here’s why: We believe that Scripture is completely trustworthy, completely true, because it is the very Word of God. We don’t believe the same thing about the liturgy. Both are good, but one is Supreme. Get to know the Supreme, and the good will pop out all the more.