C Lapide in his commentary on St Matthews Gospel writes about the idea that satan didnt know Jesus was the Son Of God, in a few places,and also of his envy that Christ was to become man -
Of the devil, namely Lucifer, the prince of all the demons. And it was just that Christ should now contend with him, as He had afore contended with him in heaven, when He cast Satan ambitiously seeking the hypostatic union, and envious that He was about to become man, down to Tartarus, as some suppose. Lucifer therefore, at this time, came forth from hell, and taking the form of a man—of a holy man, says Carthusianus—tempted Christ, (1) that he might make trial whether He were God’s own Son in very deed, and (2) that he might entice Him to sin. As therefore Lucifer, through Eve, tempted Adam, and overcame him, so he tempted Christ, and was overcome by Him. We are here taught that when the devil foresees any one will be an illustrious doctor of the Church, he is accustomed to assail him with various temptations, that he may cast him down, and destroy the harvest of souls which he sees he may reap, that he may choke the fruit in the seed, as now he strove to strangle all Christians in Christ their Parent.
If thou be, &c. The devil had heard the Father’s Voice at the Baptism of Christ—Thou art my beloved Son; yet forasmuch as he saw Him in some respects like a poor, weak, ordinary mortal, and being for that reason in doubt whether He were the very Son of God by nature, the WORD itself of the Father, or only a very eminent Son of God by adoption, he tempts Christ, and asks Him to turn stones into bread, that by His performance of the miracle, or inability to perform it, he might determine what kind of Son of God he was. For as by the Word of God all things had been created in the beginning, so by the same Word might stones be suddenly and instantly converted into bread. If therefore Christ had done this, the devil would have believed that He was the WORD of God.
So Christ made the devil suffer an illusion, who had intended to play falsely with Him. For the demon thought that if Christ were the Son of God, He would not allow Himself to be taken up and carried through the air, and by this would know whether He were the Son of God or not; but Christ, by suffering this, frustrated the demon’s plan, and left him still in doubt. Whence S. Chrysostom was of opinion that the devil supposed that he carried Christ through the air to the pinnacle of the Temple against His will, and because He was not able to resist him.