(Note: I wrote an article with the same name about a year ago. With my failing memory, there may be more of this in future! Anyway, this says some things that the other one did not, so I thought I would go ahead and post it as Part 2.)
At the end of the Lord's Prayer, sandwiched between recognition that the kingdom of heaven and all glory belong to God, is a declaration that all power (strength) ultimately comes from him as well. This is, perhaps, the most comforting line in the entire prayer, as it recognises God's role in any goodness that we might ever hope to accomplish.
There is a great old hymn ("Just a Closer Walk with Thee") that includes two relevant lines: "I am weak, but thou art strong. Jesus, keep me from all wrong." Whatever faults, failings, or weaknesses we have, there is comfort that comes from knowing that they can be overcome by God's omnipotence... whether it be his grace to forgive or his strength working to enable us to do what needs to be done.
It is like the story of the mouse and the elephant that cross a bridge: boom! boom! boom! At the other side, the mouse looks up at the elephant and says, "Boy, we sure shook that bridge, didn't we?"
Declaring that all power comes from God emphasises our total need for him at all times. As Paul wrote (I Corinthians 1:26-27): "You see your calling, brethren, how that not many ... mighty ... are called; ... but God has chosen the weak things of the world to confound the things which are mighty."
Some have falsely assumed that this declaration of our helplessness opens the door for us to give up trying to be good altogether, when quite the opposite is true. Whatever tiny grain of strength we might have has come to us from God to begin with. We are duty-bound to use that strength wisely. By planting that tiny seed of strength, by doing what we are able to do, and then by crying out to God for more of his power, we will soon find ourselves growing in his strength.
The Lord's Prayer identifies God the Father as the source of all power. Jesus said that we would receive power from the Holy Spirit (Acts 1:8). And Paul gives us that great Superman clause when he says, "I can do all things through Christ, who strengthens me." (Phillipians 4:16) So we see that the Father, the Son, and the Holy Spirit, are all there to enable us to do God's will.
It is comforting to know that this power does not ultimately come from ourselves. All we can do is all we can do; then the mighty power of God must kick in. Sometimes it can come dramatically, like a shot of heavenly adrenaline; but at other times he works more slowly, allowing us time to experience our own weakness sufficiently to appreciate the truth of our dependence on him.
Because our strength comes from God, we need to keep the channels of communication open with him, through prayer and through obedience as he enables us to obey. Sometimes I feel like all I can do is to beg for more strength, when I have come to the end of myself. It is not enough that I know what I should do; I need his strength to enable me to do it.
In some churches, people pray each week for forgiveness for the things they have done which they should not have done and for the things they have left undone which they should have done. Paul expressed this same frustration when he cried out, "The good that I would I do not: but the evil which I would not, that I do...Oh wretched man that I am! ... With my mind I serve the law of God, but with the flesh I serve the law of sin." (Romans 7:19, 24-25)
Returning to the words of that great hymn, it goes on to say, "I'll be satisfied as long as I walk (Let me walk.) close to thee." It does seem that God wants to constantly remind us that he is the source of our strength, in order to get us to reach out to him just as constantly, "praying without ceasing" for more of his strength, thus creating this closer walk with him.
