Perfectionism is impossible in the presence of a deep sense or a profound conception of sin. This movement proclaimed, it is true, only in attenuated perfectionism perfectionism merely of conduct. But this involved a correspondingly attenuated view of sin. – B.B. Warfield, The “Higher Life” Movement
The Quietist’s preoccupation, in other words, was not with sin but with nature. The Protestant, whose preoccupation was with sin, did not look for the annihilation of nature, but for the eradication cf its sin. But what the Quietist sought to be delivered from was self. It was not a purified nature he sought but a superior nature. …To the Protestant when sin is gone, nature remains — the whole of nature; sin is merely an accident to nature. To the Quietist it is only when “nature” is gone that “sin” is gone; what he is thinking of chiefly when he says “sin” is that limitation of “nature” which constitutes its essential character. There is no cure for this evil but passage into the All. -B.B. Warfield, The Mystical Perfectionism of Thomas Upham
Concerning “let go and let God” theology:
If the house catches on fire we must sit quietly in it and burn up: to walk out is to distrust God. If the boat sinks under us, we must not swim to shore, but fold our hands and sink – “let go and let God.” Here is a fully developed philosophy of irresponsibility. -B.B. Warfield, The Mystical Perfectionism of Thomas Upham
Many upcoming quotes from Warfield come from his writings against perfectionism – the idea that we can be free from sin. Pelagianism, referenced below, is that view that the will is totally free to do good such that grace is bestowed on those who merit it.
Pelagianism unfortunately does not have to wait to be imported from New Haven, and does not require inculcating – it is the instinctive thought of the natural man. -B.B. Warfield, Oberlin Perfectionism