INRI = "Jesus the Nazarene, King of the Jews"

Literally it's Iesus Nazarenus Rex Iudaeorum. Commonly written/carved on top of depictions of Jesus' cross, I'm guessing they used it as a form of crude irony... In the end it works, very easy to memorize.

The Nights in Hell bootleg is essential too!

Yes, in fact the Romans carved this epitaph on Jesus's cross because the Jews who wanted him crucified accused him of being a fraud leader, an illegitimate substitute to the King of Judea. Yet Jesus Christ presented himself as a religious leader, not as a political leader ("give to Caesar what belongs to Caesar").

As to the reason why Sarcofago chose this mention as their album title, I guess they did it to pay homage to the Jews...

OK I'm only joking, they probably thought it sounded good and blasphemous. Satanists like to use Christian terms in order to blaspheme, without realizing that they're just validating the religious worldview of their said opponents.

I think they're garbage, I don't care how much of an influence they've had. That being said, their lyrics, especially on the first album, never fail to make me laugh.

To each his own I guess. That being said The Laws of Scouge is probably Brazils finest export after Schizoprenia