St. John Chrysostom On Protection From The Devil
Please see this beautiful commentary by St. John Chrysostom (347 - 407 A.D.), one of the greatest fathers of the church. It isn't for nothing that he is called Chrysostom: "golden-mouthed."
"When the Deacon prays, 'Let us beseech for them yet more earnestly that God would deliver [the catechumens] from every evil and disordered thing,' we ask for them that they may not enter into temptation, but be delivered from every snare, a deliverance both bodily and spiritual. Then he also says, 'from every demonic sin and from every attack of the adversary,' meaning, temptations and sins. For sin easily besets, taking its stand on every side, before, behind, and so casting down. For, after telling us what ought to be done by us, namely, to be occupied in His law, to remember His commandments, to keep His judgments, he assures us next that not even is this enough, except that the Lord Himself stand by and save us. For, 'Except the Lord build the house, they labor in vain that build it' (Ps 127:1), and especially in the case of those who are yet exposed to the devil and are under his dominion.
"You who are initiated know this well. For call to mind, for instance, those words by which you renounced the devil's usurped rule, and bent the knee and deserted to The King, and uttered those awesome words by which we are taught in nothing whatever to obey Satan. Christ calls him adversary and accuser, because he both accuses God to man and us to God, and us again one to another. For once, he accused Job to God, saying, 'Does Job fear God for no reason?' (Job 1:9) At another time, he accused God to Job, 'The fire of God fell from heaven' (Job 1:16). And again, God to Adam (Gn 3:5), when he said their eyes would be opened. And to many people of this day, saying, that God does not care for the visible order of things, but has delegated your affairs to demons. And to many of the Jews he accused Christ, calling Him a deceiver and a sorcerer.
"Maybe someone would wish to hear how Satan works. When he finds a mind that is not godly, finds an unsound understanding, then, as into a soul left empty, he leads his reveling there. When someone does not remember the commandments of God nor keep His judgments, then he takes him captive and departs. Had Adam, for example, remembered the commandment which said, 'You may surely eat of every tree of the garden' (Gn 2:16) and had he kept the judgment which said, 'In the day that you eat of it you shall surely die.' it would not have fared with him as it did.
"Then the Deacon prays, 'That God would count the Catechumens worthy in due season of the regeneration of the font, of the forgiveness of sins.' For we ask some things to come now, some to come hereafter; and we expound the doctrine of the font, and in asking to instruct them to know its power. For what is said afterward familiarizes them to know already that what is there done is a regeneration, and that we are born again of the waters, just as of the womb; so that they do not say after Nicodemus, 'How can a man be born when he is old? Can he enter a second time into his mother's womb and be born?' (Jn 3:4). Then, because he had spoken of 'forgiveness of sins,' he confirms this by the following words, 'of the clothing of incorruption;' for he that puts on sonship clearly becomes incorruptible (1Co 15:53-54)."
John Chrysostom, Homilies on 2 Corinthians, 2.9