I've posted a version of this before, and didn't get much of a response. But doggone it, I'm gonna try again, but a little better presented.
The official doctrine regarding the "Faithful Discreet Slave" is that it is the remnant of anointed Christians was selected by Christ several years after his return in 1914. As stated by the Watchtower Magazine:
*** w92 12/1 p. 13 "Bring All the Tenth Parts Into the Storehouse" *** The year 1914 began what the Bible calls "the Lord’s day." (Revelation 1:10) Momentous events were to take place during that day, including the identifying of "the faithful and discreet slave" and the appointing of that one "over all [the Master’s] belongings." (Matthew 24:45-47) Back in 1914, thousands of churches claimed to be Christian. Which group would be acknowledged by the Master, Jesus Christ, as his faithful and discreet slave? That question was to be settled when Jehovah came to the temple.
Interestingly, this version of the story is a surprisingly late development.
In the 1940s, the Watchtower taught that the Society had been "acknowledged by the Master", separated out from Christendom and chosen as God's Governing body to provide "meat in due season" in 1878/1879:
The Watchtower, November 1, 1944, p.331:
The history of the past seventy years discloses that the heavenly Father and Food-Provider has by-passed the anti-Theocratic religious systems and their hierarchies and clergy, and has chosen to recognize and use humble consecrated ones who sought to be free from all religious errors and who searched for divine truth. Such lowly ones set their affections and hopes upon Jehovah’s kingdom by Christ Jesus and looked for its establishment; and they strove to keep themselves unspotted from this world. To get free at once from every bit of religious thought and practice was, of course, not to be expected of them, particularly as Jehovah God did not reveal the truth of the Holy Scriptures to them instantaneously in its fullness, but gradually.’ Thus, in 1878, forty years before the Lord’s coming to the temple in 1918, there was a class of sincere consecrated Christians that had broken away from the hierarchic and clergy organizations and who sought to practice Christianity instead of religion. The following year, namely, in July, 1879, that the truths which God through Christ provided as "food in due season" might be regularly distributed to all his household of consecrated children, this magazine, The Watchtower, began to be published, under the name " Committed to publishing the truth, it was duty-bound to expose the errors and malpractices of all religions. In turn, it suffered the abuse, misrepresentations, and opposition of all the religious systems, Catholic, Protestant and Jewish. But genuine seekers for Christianity found in its pages the hunger-satisfying spiritual food that made the Bible more and more understandable; and they looked to the Lord God and his Chief Servant Christ Jesus to supply them further "meat in due season" through its pages and columns. And Jehovah God has done so, down to this issue. Reasonably, those who were entrusted with the publication of the revealed Bible truths were looked to as the Lord’s chosen governing body to guide all those who desired to worship God in spirit and in truth and to serve him unitedly in spreading these revealed truths to other hungering and thirsting ones. However, the Theocratic principle of rule and organization was not clearly discerned back there, and a more or less democratic organization and operation of companies of consecrated Christians was permitted and practiced... [paragraph question at bottom] 6. (a) From 1879 what publication did Jehovah use in connection with dispensing spiritual food, and how did religionists and truth-seekers regard it? (b)Who were recognized as the governing body?
So what, then, was the significance of Jesus eventual inspection and selection of the "Faithful Wise Servant", several years after his "return" in 1914?
This is what the same Watchtower article had to say about the matter!
[p.331] Fulfilled prophecies make it certain that Jehovah’s Theocratic Servant Christ Jesus came to the temple in 1918. Then he entered into judgment with the consecrated servants of Jehovah. He did so in order to determine who of them should be retained in God’s service and be constituted and organized as His "faithful and wise servant" class to do the evangelistic work thenceforth. The servant’s responsibility and duty is to dispense the spiritual food as the great Theocrat gives it in due season by the unfolding of his written Word, the Bible... [p.332]...During the period from 1878 to 1918 Jehovah’s devoted servants were endeavoring to act unitedly in doing the witness work pictured by that of Elijah the prophet and hence referred to as "the Elijah work". Like Elijah’s work, it was against religion or demonism and for the vindication of God’s name. This work, conducted under the leadership of Christ Jesus, came to an end in 1918, when he came to the temple as Jehovah’s Messenger and Judge. (See Malachi 3: 1.) The judgment tests which he then and there applied separated out from Jehovah’s professed servants an "evil servant" class, which followed after man-worship, selfish ambitions, and self-righteousness, and which aimed after the control of the governing body. A remnant manifested purity of heart and devotion to the Lord God and to his Theocratic organization and the interests of his kingdom. This faithful remnant was approved under the judgment trial, and Christ Jesus the King gathered them unto unity with himself at the temple. He adjudged these faithful anointed servants of Jehovah God to be the "faithful and wise servant" class under himself as Head. To them he committed the interests of the Kingdom. That is, he laid upon them the duty and privilege to carry on the evangelistic work as Jehovah’s witnesses in ’preaching the evangel of the kingdom in all the habitable earth for a witness to all the nations’. This they must do, down to the battle of Armageddon, when the Kingdom will destroy all the enemies of The Theocracy and then the millennial reign of Christ Jesus will begin. [question at bottom of page] 9. Under what work were Jehovah’s servants doing down till 1918? and at its end what class was separated out from among them?
Jesus' inspection, simply put, was to weed out and discredit those who were disloyal and/or a threat to Rutherford's new heirarchy! [namely, those remaining loyal to Russell]
It had nothing to do with inspecting which religion on earth had the most truth. No one outside of "Jehovah's consecrated servants" were even in the running! It had nothing to do with the "thousands of churches" who "claimed to be Christian". The only difference before the inspection and after inspection was that Jesus finally "kicked out" the bad apples from the "anointed class"!
Thus, the WTS had a way to explain why those not loyal to the organization were not truly anointed anymore.
And there you have it...the REST of the story.