Check out my discussion of this text and what it likely meant to the Jewish Matthean community in Syria:
In short, Paul's antinomianism is the probable focus of this passage, and indeed this was a chief concern in the Sermon on the Mount: "Do not imagine that I have come to abolish the Law or the Prophets. I have come not to abolish but to complete them. I tell you solemnly, till heaven and earth disappear, not one dot, not one little strike, shall disappear from the Law until its purpose is achieved. Therefore, the man who infringes even one of the least of these commandments and teaches others to do the same (i.e. Paul, for example) will be considered the least in the kingdom of heaven" (Matthew 5:17-19; compare James 2:10, and the refutation of Paul's antinomianism in v. 14-26). In Ebionite writings probably connected to the Syrian Matthean community (because of the halakic authority recognized in Apostle Peter), Paul was also described as the false apostle who comes as a "sheep in wolves' clothing". In reading 2 Corinthians last night, I also thought of Paul's criticism of his Jewish-Christian opponents in Achaia, the ultra-apostles that he calls "false apostles, dishonest workmen disguised as apostles of Christ" (11:13). Since Paul repeatedly echoes the criticisms of his opponents (cf. 10:10, 11:4, 12-14; compare also Galatians and 1 Corinthians 1:12, 3:4, 22), it is quite striking that Paul's motif of DISGUISE evokes closely the same criticism by his Jewish-Christian opponents: "If Satan himself disguises himself as an angel of light, there is no need to be surprised when his servants (that is, the "false apostles" of v. 13), too, disguise themselves as servants of righteousness" (2 Corinthians 11:14). This compares well with Matthew 7:15: "Beware of false prophets who come to you disgused as sheep but underneath are ravenous wolves." We may also compare with the Ebionite Itinerary of Peter:
"Our Lord and Prophet, who has sent us, declared to us that the wicked one, having disputed with him forty days (i.e. Satan the Devil), and having prevailed nothing against him, promised that he would send apostles from among his subjects to deceive. Therefore, above all, remember to shun any apostle or teacher or prophet who does not first accurately compare his preaching with that of James , who was called the brother of my Lord, and to whom was entrusted to administer the church of the Hebrews in Jerusalem....He who has sent us said that many will come in sheep's clothing, in inwardly they are ravenous wolves. By their fruits you shall know them" (Hom. 11:35).
It is generally agreed that this passage refers to Apostle Paul, particularly in its allusion to antinomianism in the reference to James the Just (in Galatians 2:7-10, Paul insists that James and Cephas/Peter agreed with his "Good News as I preach it"). The anti-Pauline rhetoric is even more explicit in the anti-Pauline Epistula Petri 2.4-5.
Paul's statement about Satan transforming himself into an angel of light, by the way, is quite Jewish and we may note the identical phrasing in the haggadic Life of Adam and Eve (c. first century AD): "And eighteen days passed by; then Satan was wroth and transformed himself into the brightness of angels" (9:1; cf. Apocalypse of Moses 38:1).