All confidence is empty, except confidence in mercy...

In the Lord's Prayer the saints ask for the forgiveness of sins.  Therefore, even the saints have sins.  The innocent shall not be innocent.

"For the LORD your God is a consuming fire, a Jealous God." (Deuteronomy 4:24)

"Be silent, all flesh, before the Lord." (Zechariah 2:13)

"All flesh is grass, and all its beauty is like the flower of the field.  The grass withers, the flower fades when the breath of the Lord blows on it." (Isaiah 40:6-7)

Namely, flesh and righteousness of the flesh cannot endure God's judgment.  Jonah 2:8 also says, "Those who pay regard to vain idols forsake their hopes of steadfast love," that is, all confidence is empty, except confidence in mercy.  Mercy delivers us; our own merits, our own efforts, do not.  So Daniel also prays:

"For we do not present our pleas before You because of our righteousness, but because of Your great mercy.  O Lord, hear; O Lord, forgive.  O Lord, pay attention and act.  Delay not, for Your own sake, O my God, because Your city and Your people are called by Your name." (Daniel 9:18-19)

So Daniel teaches us in praying to seize mercy, that is, to trust in God's mercy not our own merits before God.
~BOC, AP, V (III), 208-210

The work of the old Adam...

In short, the old Adam encourages us to have all kinds of evil lusts, which cling to us by nature and to which we are moved by the society, the example, and what we hear and see of other people. They often wound and inflame even an innocent heart.
~BOC, LC, III, 102

Standing one day and falling the next is the nature of our life...

Although we have received forgiveness and a good conscience and are entirely acquitted, yet our life is of such a nature that we stand today, and tomorrow we fall.  Therefore, even though we are godly now and stand before God with a good conscience, we must pray again that He would not allow us to fall again and yield to trials and temptations.
~BOC, LC, III, 100

Our need for the comfort of the Gospel...

...the purpose of this prayer is that we may recognize and receive such forgiveness.  The flesh in which we daily live is of such a nature that it neither trusts nor believes God.  It is ever active in evil lusts and devices, so that we sin daily in word and deed, by what we do and fail to do.  By this the conscience is thrown into unrest, so that it is afraid of God's wrath and displeasure.  So it loses the comfort and confidence derived from the Gospel.  Therefore, it is always necessary that we run here and receive consolation to comfort the conscience again.
~BOC, LC, III, 88-89

The devil's will and purpose and all our enemies shall and must fail...

We have this comfort and confidence: the devil's will and purpose and all our enemies shall and must fail and come to nothing, no matter how proud, secure, and powerful they know themselves to be.  For if their will were not broken and hindered, God's kingdom could not remain on earth nor His name be hallowed.
~BOC, LC, III, 70

The devil chafes and rages as a fierce enemy against us with all his power and might...

No one can believe how the devil opposes and resists these prayers.  He cannot allow anyone to teach or to believe rightly.  It hurts him beyond measure to have his lies and abominations exposed, which have been honored under the most fancy, sham uses of the divine name.  It hurts him when he himself is disgraced, is driven out of the heart, and has to let a breach be made in his kingdom.  Therefore, he chafes and rages as a fierce enemy with all his power and might.  He marshals all his subjects and, in addition, enlists the world and our own flesh as his allies.  For our flesh is in itself lazy and inclined to evil, even though we have accepted and believe God's Word.  The world, however, is perverse and wicked.  So he provokes the world against us, fans and stirs the fire, so that he may hinder and drive us back, cause us to fall, and again bring us under his power.  Such is all his will, and mind, and thought.  He strives for this day and night and never rests a moment.  He uses all arts, wiles, ways, and means that he can invent.

~BOC, LC, III, 62-64

The eternal inestimable treasure in God's kingdom come to us...

From this you can see that we do not pray here for a crust of bread or a temporal, perishable good.  Instead, we pray for an eternal inestimable treasure and everything that God Himself possesses.  This is far too great for any human heart to think about desiring, if God had not Himself commanded us to pray for the same.  But because He is God, He also claims the honor of giving much more and more abundantly than anyone can understand.  He is like an eternal, unfailing fountain.  The more it pours forth and overflows, the more it continues to give.
~BOC, LC, III, 55-56

God arranges the words and form of our prayers, places them on our lips...

...God expects us and He Himself arranges the words and form of prayer for us.  He places them on our lips for how and what we should pray, so that we may see how heartily He pities us in our distress, and we may never doubt that such prayer is pleasing to Him and shall certainly be answered.
~BOC, LC, III, 22

God commands us to pray because He desires that we call upon Him...

Indeed, the human heart is by nature so hopeless that it always flees from God and imagines that He does not wish or desire our prayer, because we are sinners and have earned nothing but wrath.  Against such thoughts, we should always remember this commandment and turn to God, so that we may not stir up His anger more by such disobedience.  For by this commandment God lets us plainly understand that He will not cast us away from Him or chase us away.  This is true even though we are sinners.  But instead He draws us to Himself, so that we might humble ourselves before Him, bewail this misery and plight of ours and pray for grace and help.
~BOC, LC, III, 10-11

God does not allow prayers to be in vain or lost...

Furthermore, He will not allow our prayers to be in vain or lost.  For if He did not intend to answer your prayer, He would not ask you to pray and add such a severe commandment to it.
~BOC, LC, III, 18

God faithfully provides all that His creation needs...

You see, in this way, God wishes to show us how He cares for us in all our need and faithfully provides for us also for our earthly support. He abundantly grants and preserves these things, even for the wicked and rogues. Yet, He wishes that we pray for these goods in order that we may recognize that we receive them from His hand and may feel His fatherly goodness toward us in them.
~BOC, LC, III, 82-83