For a while when I started teaching the Catechism, I wasn't sure what to do with the Lord's Prayer. Well, I taught it - but I couldn't fit it in with the order, the system. There's such a beautiful pattern to the catechism.
You have the 10 commandments - all about what we ought to do and fail in.
You have the Creed - all about what God does for us.
You have Baptism, Absolution, and the Supper - How God comes to us with His salvation.
What then is prayer? Is it something that we *do* for God? That's not how it's taught. Is it a sacrament? Well, no. Rhetorically, how does it fit - or does it fit? Is it just there because Jesus taught it to us?
The Lord's Prayer serves, via Luther's explanations, as a hinge between what comes before it (the 10 commandments and the Creed) and the Sacraments which follow. It is the hinge between the overarching ideas of Law and Gospel and the sacraments - a study in how all these things impact our lives.
Consider petitions 1-3. Hallowed be Thy Name, Thy Kingdom Come, Thy will be done on earth as it is in heaven. Each of these petitions simply sums up the 10 commandments - as Luther points out in their explanation. Each of these explanations show how we ourselves do not hallow God's name, how we disdain His kingdom, and how we try to thwart God's will. This is Law - and it is an application of Law to our lives.
Then we have Petition 4 - Give us this day our daily bread - and the explanation looks almost exactly like the 1st Article.
Then we have Petition 5 - Forgive us our trespasses, as we forgive those who trespass against us. Deals with the 2nd Article.
Then we have Petition 6 - And lead us not into temptation - Deals with the themes of the 3rd article - being preserved and kept by the Holy Spirit.
So, in the first 6 petitions we have a recapping of everything that has come before, the 10 commandments and the Creed. And then in the 7th, we hear this - But deliver us from evil.
Where and how are we delivered from Evil? In the Sacraments. The 7th Petition thrusts us forward into the concrete ways in which God does deliver us from Evil.
The Lord's Prayer is the hinge of the Catechism - it shows how all this theology stuff isn't far away but is the shape of our daily lives, and it moves us from what could become just an intellectual exercise in theology towards the Sacraments, where we participate in salvation.