In the Greek text this petition reads thus: Deliver or preserve us from the Evil One, or the Malicious One; and it looks as if He were speaking of the devil, as though He would comprehend everything in one so that the entire substance of all our prayer is directed against our chief enemy. For it is he who hinders among us everything that we pray for: the name or honor of God, God's kingdom and will, our daily bread, a cheerful good conscience, etc.
Therefore we finally sum it all up and say: Dear Father pray, help that we be rid of all these calamities. But there is nevertheless also included whatever evil may happen to us under the devil's kingdom -- poverty, shame, death, and, in short, all the agonizing misery and heartache of which there is such an unnumbered multitude on the earth. For since the devil is not only a liar, but also a murderer, he constantly seeks our life, and wreaks his anger whenever he can afflict our bodies with misfortune and harm. Hence it comes that he often breaks men's necks or drives them to insanity, drowns some, and incites many to commit suicide, and to many other terrible calamities. Therefore there is nothing for us to do upon earth but to pray against this arch enemy without ceasing. For unless God preserved us, we would not be safe from him even for an hour.
Hence you see again how God wishes us to pray to Him also for all the things which affect our bodily interests, so that we seek and expect help nowhere else except in Him. But this matter He has put last; for if we are to be preserved and delivered from all evil, the name of God must first be hallowed in us, His kingdom must be with us, and His will be done. After that He will finally preserve us from sin and shame, and, besides, from everything that may hurt or injure us.
Thus God has briefly placed before us all the distress which may ever come upon us, so that we might have no excuse whatever for not praying. But all depends upon this, that we learn also to say Amen, that is, that we do not doubt that our prayer is surely heard and [what we pray] shall be done. For this is nothing else than the word of undoubting faith, which does not pray at a venture, but knows that God does not lie to him, since He has promised to grant it. Therefore, where there is no such faith, there cannot be true prayer either.
It is, therefore, a pernicious delusion of those who pray in such a manner that they dare not from the heart say yea and positively conclude that God hears them, but remain in doubt and say, How should I be so bold as to boast that God hears my prayer? For I am but a poor sinner, etc.
The reason for this is, they regard not the promise of God, but their own work and worthiness, whereby they despise God and reproach Him with lying, and therefore they receive nothing. As St. James says [1, 6]: But let him ask in faith, nothing wavering; for he that wavereth is like a wave of the sea, driven with the wind and tossed. For let not that man think that he shall receive anything of the Lord. Behold, such importance God attaches to the fact that we are sure we do not pray in vain, and that we do not in any way despise our prayer.