But there you're doing it again. You never were one of those "workers of iniquity", even before you came to Christ Jesus. If you had been, you would have been seeking to destroy the Faith even now. Those workers are different than the average sinner who doesn't know Christ. Those workers are the devil's own.
And Apostle Paul's kinsmen Jews there are not that "mystery of iniquity" either.
1 Chron 2:55
55 And the families of the scribes which dwelt at Jabez; the Tirathites, the Shimeathites, and Suchathites. These are the Kenites that came of Hemath, the father of the house of Rechab.
KJV
Gen 15:18-21
18 In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates:
19 The Kenites, and the Kenizzites, and the Kadmonites,
20 And the Hittites, and the Perizzites, and the Rephaims,
21 And the Amorites, and the Canaanites, and the Girgashites, and the Jebusites.
KJV
The scribes among Israel were peopled by the Kenites, a people that dwelt in the lands of Canaan when the children of Israel first entered those lands, and God told Israel to literally destroy 7 of those nations in Deut.20.
It was the scribes in Jesus' day that were one of the main contenders that wanted to murder Him.
1 Kings 9:19-21
19 And all the cities of store that Solomon had, and cities for his chariots, and cities for his horsemen, and that which Solomon desired to build in Jerusalem, and in Lebanon, and in all the land of his dominion.
20 And all the people that were left of the Amorites, Hittites, Perizzites, Hivites, and Jebusites, which were not of the children of Israel,
21 Their children that were left after them in the land, whom the children of Israel also were not able utterly to destroy, upon those did Solomon levy a tribute of bondservice unto this day.
KJV
Israel disobeyed God's Deut.20 command to literally wipe out those Canaanites. So He allowed them to creep into Israel to test them with (Judges 2 & 3). There in Solomon's day, they still were among Israel, having become bondservants. Eventually they would become the Nethinims (temple servants), and the scribes and Pharisees that wanted to murder our Lord Jesus. Those are not Paul's brethren he was speaking about, those are Canaanites having crept in.
Zech 14:20-21
20 In that day shall there be upon the bells of the horses, HOLINESS UNTO THE LORD; and the pots in the LORD's house shall be like the bowl's before the altar.
21 Yea, every pot in Jerusalem and in Judah shall be holiness unto the LORD of hosts: and all they that sacrifice shall come and take of them, and seethe therein: and in that day there shall be no more the Canaanite in the house of the LORD of hosts.
KJV
That is Millennial timing when Christ's Kingdom is reigning with His elect on earth over all nations.
When our Lord Jesus revealed the "synagogue of Satan" in Rev.2:9 and Rev.3:9, He said they lie and say they are Jews but are not. That means they CLAIM to be Jews, but instead they are the hidden 'tares' of the parable of the tares of the field, i.e., the children of the Wicked one, Satan, meaning his servants, his own elect.
If you don't understand about their existence in God's Word, then there is much of God's Word you will not truly understand.