Galatians 1:9
Galatians 1:99As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be under a curse!
Applied to Christendom — the churches are held to preach a corrupted gospel departed from apostolic teaching, and this verse is taken as the apostolic verdict on them. The Watchtower's own message, the good news of the Kingdom, is understood as the restoration of what was originally preached.
Accept the test completely — Paul says it twice in two verses, so he meant it. The only question is what the standard is that a message gets measured against, and Paul gives it in the same letter's family of teaching. He defines the gospel at , in writing, so it can be checked: Christ died for our sins according to the Scriptures, was buried, and was raised on the third day according to the Scriptures, attested by many eyewitnesses. That is the message by which he says the Corinthians are being saved. So walk through those verses in the NWT with a Witness and then ask, without pressing: does the message you brought me this morning match this one? Kingdom rule, a restored earth, and faithful obedience are consequences of the gospel — but Paul's definition is about a death and a resurrection. The test cuts in every direction, which is what makes it fair to apply. Paul included himself and even an angel from heaven in it. Compare , , .