This doxology isn't found in the earliest Greek manuscripts, and apparently was not part of the original prayer. In some Christian traditions, the doxology isn't used. However, it is a fitting conclusion, and sums up a number of important facets of the prayer.
The doxology is given as the reason for our praying. The word "for" ties it, not just to the prayer for deliverance, but to the whole model prayer.
Why pray? The answer is here, for if God isn't God, if life doesn't come from him and go to him, if this world is without Creator and moral Ruler who not only hears and answers prayer but to whom we are accountable for our lives... then there's not much use praying at all!
But, specifically, why pray like this? The answer is here. It is because the Kingdom, Power and Glory belong to God that we want his name to be kept holy, his Kingdom to come and his will to be done. This is also the conviction that motivates our petitions for daily bread, for forgiveness, for freedom from temptation and deliverance from evil.
Revelation 5 gives us a little glimpse into the praise of heaven itself. The Lamb who was slain is worthy, not only to open the scroll (v. 9), but "to receive power and wealth and wisdom and strength and honour and glory and praise!" (v. 12). And "every creature in heaven and on earth and under the earth and on the sea, and all that is in them" join in singing, "To him who sits on the throne and to the Lamb be praise and honour and glory and power, for ever and ever!" (v.13).
His Son he sent to save us -
the ransom price was paid
as to the cross we nailed him
and in the grave he lay!
But then he rose victorious,
for sin is overthrown,
to take his station glorious
beside the great white throne.
To you is praise and honour due -
you are the Lord of all!
Before your glorious majesty
all earthly rule shall fall!
There are other "earthly rules", but the Kingdom belongs to the Lord. The faith that has asked for the coming of the Kingdom affirms that the Father is clearly and absolutely the King.
We see the coming of the Kingdom in the impact of the Gospel on individuals and within the structures of society, but the fact of God's Kingship is not dependent on the success of our evangelism or the prevalence of goodness. The rejection of God's Rule by so many today does not make him any less really the King. This reflects rather on those who reject him.
Think about the parable of the gold coins (Luke 19.11-27). This high ranking man was going into a far country to be made king. His ten servants were each given a gold coin to trade with in his absence. The story records the wise action of two of the servants and the praise (and responsibility) they received on their master's return. But another servant had done nothing except keep his gold coin hidden in his handkerchief. He earned his master's disfavour. But there is another strand to this story. We read that "But his subjects hated him and sent a delegation after him to say, 'We don't want this man to be our king' " (v. 14). But did that make him any less their king? They came under the king's severe judgment.
Jesus told that parable on the way up from Jericho. They were almost at Jerusalem and the people were supposing "that the Kingdom of God was going to appear at once" (v. 11). The story is followed by the triumphal entry into Jerusalem - Palm Sunday (vv. 28ff).
Yours is the Kingdom, Lord - no matter what people may do! And we are to pray and to live, acknowledging that we are accountable to you!
Again and again the Scriptures remind us that "our God is able..." For the most powerful earthly ruler, there are still a great many limitations. He may go to war with a large measure of confidence, yet the outcome is never entirely guaranteed. He has "power" in a relative sense, but only God has "the Power" absolutely.
When God does not grant our requests in prayer because we have not asked according to his will, or when in his wisdom his answer seems delayed, we are inclined to question the value of prayer - can God really hear and answer? But God isn't our message-boy - his Power fulfils his will in his time.
And when God has shown patience and restraint toward a sinful generation, we have interpreted that as weakness and have failed to grasp his love - or to hear his call to serve!
The Lord said through his prophet Isaiah, "As the rain and the snow come down from heaven, and do not return to it without watering the earth and making it bud and flourish, so that it yields seed for the sower and bread for the eater, so is my word that goes out from my mouth: It will not return to me empty, but will accomplish what I desire and achieve the purpose for which I sent it" (Isaiah 55.10-11).
Yours is the Power, Lord!
The goal of our praying and of our living is not our self-satisfaction, but the glory of God. This is what our lives were designed to be. This is what we have failed to reach because of sin (Rom. 3.23).
We see God's Glory in his Rule established and in his Power made visible. But God is glorious in himself - absolute in truth, in beauty, in purity and in love. The immediate response to God is worship.
Yours is the Glory, Lord! Before you, we bow in worship and submission!
The Kingdom, the Power and the Glory are yours for ever! You, Lord, are the focus of true praying and true living now and for ever!