Evangelical,
The ecumenicism you are excoriating is a relic from the past. Once again you are taking your riff from something Witness Lee taught long ago. Have you no inspiration other than things a man dead for twenty years taught?
You are succumbing to the fallacy of the excluded middle, aka
false dilemma. You say either everyone will spontaneously "leave all the divisions" (which we both know is code for joining the LCM) or they will succumb to a murky, marshy "unity" where everyone must have the blood of the lowest common denominating sin on their heads.
You missed the middle you excluded in your fallacious reasoning.
What is actually happening today is that God is working out unity in the community churches and some denominations. Is it according to the theoretical idealism of the LCM? No, but that ideal is not going to happen anyway, so who cares. Fact is, it's just a unobtainable fantasy by which the LCM discredits everything but what they want to believe they are. (Which they aren't, but that's another story.)
But neither is it according to your cynical excluded middle alternative of man-made ecumenicism. Oneness is being seen these days. Not just shaking hands over the fence, but commitment, cooperation and a genuine desire to see God break out to a level never before really seen. It is happening.
So I don't buy your cynicism. And I see it for what it really is--another attempt to discredit everything but the LCM. Continue to throw stones from your ivory tower. Continue to be part of the problem rather than the solution. Continue to be a Pharisee, if that's what floats your boat. Meanwhile God is working...