"The Ministry of the age."

I have had several discussions with several ministry minions, and there is this wild (imo) idea, that without the ministry of Witness Lee, there is just no way for the Lord to come back, there is no way for the church to be really built up etc. Of course, since I am outside of the bubble, I know this to be false, because I am a witness of the Lord building up his Body in my area in several different house churches that is not affiliated or have even heard of Witness Lee.

So my questions is this; What is the best way to engage into fruitful conversations with Christians/Local Church followers, using the Word to debunk this doctrine, to help them out of this system of error?

Any thoughts or comments welcome :-)