Now we do not hesitate to say, that this can never be done by a person, who has not seriously and fully consecrated himself to God. Not to consecrate ourselves to God, with a fixed purpose to do his will, is the same thing, as it seems to us, or at least is essentially the same thing, as deliberately to sin against God. Certain it is, that he, who is not willing to consecrate himself to God with a full purpose to conform to his designs, is willing to sin against him, when a favorable opportunity presents. It is not too much to say, that he is conscious, and must be conscious, at the present moment, of sinning against God in his heart. It is obviously impossible, that a person in this state of mind, if he has any proper conceptions of God’s law and of God’s character, should have a full assurance of being the subject of his acceptance and favor. No person, therefore, whatever other degrees of faith he may have, can enjoy full assurance of faith, who is not conscious, that he has in all things, and for all time to come, and with all the powers of perception and volition which he possesses, consecrated himself to God without reserve.
Dr. Hopkins, “would have reason to call in question.” The evidence in the case is not what might be called by a term, which numerous facts in ecclesiastical history render almost an indispensable one, “apparitional” evidence; that is to say, the evidence of outward appearances and manifestations, the evidence of sights and sounds, of dreams and visions, upon which so many rely; but upon which the Bible no where authorizes us to place reliance. Nor is it what may be called “emotional evidence,” the evidence of mere joy and sorrow, upon which so many others rely; but which we obviously cannot rely upon with entire confidence, because our joys and sorrows are very variable, and may arise from causes, which are not religious, although they are frequently mistaken for such. It is the evidence, the divine and infallible evidence, of God’s Spirit testifying through the principle of faith; and that faith, which exists distinctly and quietly in our consciousness, just as any other analogous state of mind does, resting upon God’s immutable Word. If we have given ourselves to God to be wholly and forever his, then we have no reason for doubting, (and the testimony of the Holy Spirit revealed in the act of faith is in accordance with the fact,) that we are the children of God, since we have God’s immutable word, that we are such. “Come ye out from among them, and be ye separate, and touch not the unclean thing; and I will receive you, and will be a father unto you, and ye shall be my sons and daughters, saith the Lord Almighty.” 2 Corinthians 6:17, 18.
— edited from The Life of Faith (1852) Part 1, Chapter 16.