He has protected the Church. That “batch of leaders” were “Judas’s. There was one that God allowed during the life of His beloved Son, and there are more today.
God is sifting.
In the world you shall have tribulation.
It is here, ma’m.
Where does the church exist without people?
What mechanism establishes doctrine to follow if men don’t do it?
Is there some kind of entity somewhere that is outside the human component that you adhere to?
Which church?
And how has He protected it if He has allowed the current crop of leaders?
How is that protecting anything?