Well, since the WTBTS "litter-ature" has informed people almost 4000 times about "true Christian/s", then it would appear that they must be the assigned experts to judge any hypocritical "wolves in sheep's clothing".
Thank goodness the Bible confirms that the FDS has been given the privilege to say who is or isn't a Christian!
2 Corinthians 5:10 says (probably in the New version of the NWT) "For we must all be made manifest before the judgment seat of the Governing Body, that each one may get his award for the things done through the body, according to the things he has practiced, whether it is good or vile."
Or in simple terms, it's like saying to Christ, "Don't worry yourself, we'll do the judging for you!!".