It wasn't a unique teaching they had before 1919 that made Jesus choose them. The faithful and discreet slave through various trials and errors came to an accurate knowledge of truth and loyally submitted themselves to do God's will.
If it wasn't a unique teaching before/in 1919 that made Jesus choose them, please explain exactly the following:
In/before/during 1919, what exactly was the "accurate knowledge of the truth" which the Bible students possessed, that caused them to "submit themselves to do God's will", that resulted in Jesus choosing them?
And, one more thing, in/before/during 1919, who/what exactly represented the Faithful and Discreet slave?
Questions submitted with full honesty, humility and willingness to listen to reason.