In 2 Cor. 2.10-11, Paul notes that he is on the look-out against Satan’s tactics.
Later on in the same letter he cautions his readers as well to guard against Satan. This warning comes when he discusses rival Christian missionaries whom he sarcastically terms “Super-Apostles.” “Such boasters,” he says, “are false apostles, deceitful workers, disguising themselves as apostles of Christ. And no wonder! Even Satan disguises himself as an Angel of Light. So it is not strange if his ministers also disguise themselves as ministers of righteousness. Their end will match their deeds” (2 Cor. 11.13-15).
We are to assume that Satan is different from an Angel of Light, though able to pose as one. Can we say that he is an Angel of Dark? We do not know, but we can be certain of one thing: there is no question of the sort of dualism met with at Qumran, where the Angel of Light is opposed to the Prince of Dark. Here Satan poses as an Angel of Light (and perhaps it would be better not to capitalize “angel” and “light”). The phrase used here, angelos photis, could be a Semitism, by which a genitive noun (“of light”) is used for an adjective, “shining”;
and, of course, “angel” could be a human rather than supernatural messenger, so that it could mean something like “an informative visitor.”
Just after speaking of not being outwitted by Satan, Paul characterizes himself as a genuine speaker of the word of God and seemingly likens himself to an Angel of the Presence, for he says that he is “like those sent from God and standing in His Presence” (2 Cor. 2.17). Elsewhere, in his Letter to the Galatians, he speaks (in an exaggerated fashion, admittedly) of the possibility that an Angel from Heaven might preach a false gospel (Gal. 1.8). He did the same in his earlier letter to the Corinthians, in his celebrated praise of love: “If I speak in the tongues of mortals and of Angels, but do not have charity, I am a noisy gong or a clanging cymbal” (1 Cor. 13.1).
At the very least, we can conclude that Paul is saying that Satan encourages dissension among the followers of Christ, and does so in a devious and dangerous way. But why he would do so is not entirely clear.