It's about truth, in this case relating to false Jews.
I know thy works, and tribulation, and poverty, (but thou art rich) and I know the blasphemy of them which say they are Jews, and are not, but are the synagogue of Satan
The context for this is the message to the first church, which also relates to truth - the liars who were false apostles who were rejected at Ephesus (verse 2).
But when divers were hardened, and believed not, but spake evil of that way before the multitude, he departed from them
, and separated the disciples, disputing daily in the school of one Tyrannus.
Paul's lie to the Sanhedrin is readily apparent:
But when Paul perceived that the one part were Sadducees, and the other Pharisees, he cried out in the council, Men and brethren, I am a Pharisee, the son of a Pharisee: of the hope and resurrection of the dead I am called in question
Them take, and purify thyself with them, and be at charges with them, that they may shave their heads: and all may know that those things, whereof they were informed concerning thee, are nothing; but that thou thyself also walkest orderly, and keepest the law
The tribe of Benjamin aligned with Judah in the separation from the house of Israel, so Paul's claim implied a claim to the house of Judah, i.e. the "Jews"
I say then, Hath God cast away his people? God forbid. For I also am an Israelite, of the seed of Abraham, of the tribe of Benjamin.
But the soul that eateth of the flesh
of the sacrifice of peace offerings, that pertain unto YHWH, having his uncleanness upon him, even that soul shall be cut off from his people.
For, lo, I will raise up a shepherd in the land, which shall not visit those that be cut off, neither shall seek the young one, nor heal that that is broken, nor feed that that standeth still: but he shall eat the flesh
of the fat, and tear their claws in pieces.