Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? 2 Corinthians 6:14.
Dear Sister _____: I will not delay writing you that which the Lord brings to my mind. Your case was presented to me two years ago. I then saw you were a deceived woman. You thought you had clear light from God, but it was darkness. You have had views and an experience peculiar to yourself and not in harmony with the people whom God is leading...
There is no such thing as an instantaneous sanctification. It is an every-day work. Says Paul, “I die daily” (1 Corinthians 15:31). He received a conversion daily to God. As the truth and Spirit of God revealed to him the defects in his character, he put away his wrong, died to self, and cleansed himself “from all filthiness of the flesh and spirit, perfecting holiness in the fear of God” (2 Corinthians 7:1)...
Your peculiar ideas have had so powerful a control upon your mind [that] you could not dwell upon anything else. In meeting, you thought it your special duty to urge your opinions. You have taken your position above the church as though you were exalted and in the light and [as though] they must come up to your position, receive your views. You are fanatical; you have not a healthy imagination. Your influence will do harm and only harm, unless you become humble and teachable...
Satan is most successful when he can cover up minds in this kind of pious, sanctified consecration which has no part in the sanctification brought to view in the Word of God. It is, in short, a spurious article, that article [that] you possess. You received your views of sanctification from those who claim to be sanctified and holy, who have no love for the law of God and who have no love for His appearing. You received your light from a corrupt source; the stream that came from a corrupt fountain is impure.
As I write to you, your case is more plain and clear before me. You have allowed your views of sanctification to unite you to those who were grossly corrupt. You have not obeyed the Word of God and abstained from all appearance of evil. Satan has desired your soul that he might sift you as wheat. Your “holy, sanctified union” (as you have termed it) with individuals has been a delusion of Satan...
You have been led through your perverse ideas of sanctification to depart from the Word of God. You have a work to do to break all in pieces and give up your experience in the past few years and become as a little child and be converted, be humble and teachable that God may lead you.—Letter 10, August 5, 1870, to a church member in New York State.
Reference: E.G. White, "The Upward Look," p. 231.