As much as I approach this thread with serious hesitation, I think I at least wanted to offer a straightforward response here.
The title of this thread says it will provide "evidence". So, at this point, what needs to be posted here is SCRIPTURAL PROOF that the agents of the Watchtower Society--Joseph F. Rutherford and his associates--were chosen by Jesus Christ in the year 1919 to provide spiritual food for God's household, to the exclusion of all other Christians on the face of the earth.
However, the problem is that this is an assumption based on an understanding taught by the very people claiming to be the "faithful slave" class. Matthew 24:45-47 makes no mention of the year 1919 as having any significance or pertaining to the prophecies made in Matthew 24. Jesus said, "Who really is the faithful and discreet slave?" There is a question mark there, indicating that this is not a statement. Jesus did not say, "There will be a faithful slave CLASS, CHOSEN BY ME IN 1919 TO PROVIDE SPIRITUAL FOOD". That would be a prophetic statement. Jesus names no person or group of persons as definitely fulfilling this role; he asks a question. Only the master can appoint the slave over his domestics. Thus, any human informing others that he and his buddies fulfill this role is really only a group of humans saying it; it does not actually prove anything. What makes it worse is that immediately after this supposed appointment in 1919, Rutherford and his associates commence a worldwide campaign of disseminating a message that is demonstrably false, a message no longer taught and hardly spoken of today. Jesus Christ would have given any such "slave class" clearer instructions and a definite message from the start.
The context, Matthew chapter 24, demonstrates that Jesus had already transitioned from giving specific details about the sign of the end to giving illustrations highlighting the need for obedience, sharing the good news, and watchfulness. The "faithful slave" is a term used metaphorically, not a term used to convey authority to a group of men who would be members of a governing body.
"Governing body" is a term not used in scripture, like "organization", "John class", "theocracy", and quite a few others. To govern is to rule. Paul warned first-century Christians who thought they had started ruling without the rest of the Christians back then. (1 Cor. 4:8) As of today, only Jesus Christ rules as king, so far as any human can verify. And even that is verifiable only by eyewitnesses who lived 2,000 years ago. Any other claims regarding the resurrection of 'anointed' ones are even less verifiable. The apostles made their decision regarding circumcision in Acts 15 in conjunction with the older men in the congregation of Jerusalem. It was a decision that had already been made by holy spirit; the evidence was undeniable. The apostles were only informing the congregations of what had already been determined by an authority far higher than they--the holy spirit. Unlike the Governing Body of Jehovah's Witnesses today, they involved the older men and probably the entire congregation in the discussion they were having; there were no closed-door sessions where they had to wonder what was being discussed. The fact that this sort of meeting is never mentioned again in scripture is an indication that it was more likely the exception and not the rule as far as the congregation back then. Paul spends Galatians 1-2 explaining that he didn't consider himself subject to the apostles at all, as his appointment came from Jesus Christ directly. The Governing Body of JWs would have summarily disfellowshipped him had he done something like that today.
Worse still is the fact that Jehovah's Witnesses actually denied the existence of a governing body over the early Christian congregation as late as 1929 in The Watchtower--10 years after the "slave class" was appointed!
Even the Society itself provides more evidence than you have thus far provided in this thread. As the final authority for Jehovah's Witnesses is presumably the Bible, you need to use the Bible to prove your points.
--sd-7