"And this is the confidence that we have in Him, that, if we ask any thing according to his will, he heareth us. And if we know, [that is, have full faith or confidence in him,] that he heareth us, whatsoever we ask, we know that we have the petitions that we desired of him." 1 John v: 14.
The doctrine of these important passages is this. In consecrating ourselves to God, and in praying sincerely for those things which are agreeable to the will of God, such as our sanctification and those Christian graces which are implied in sanctification, we may be certain that they will be given to us, and that they are now given to us, if we have no doubt in God's word.
The certainty of the result, when the condition on which it depends is fulfilled, viz. a full belief of the truth of the divine declaration, is necessarily involved in the veracity of God; and not as is sometimes supposed, in the mere fact of believing. This is an important distinction. It is God's everlasting TRUTH, and nothing but his truth, which is the real foundation of the great principle involved in these passages.
Nevertheless, it must be admitted, that the result cannot take place without the specific act of faith; because the defect or want of such faith necessarily makes a separation between God and our souls, and especially because the promise of God, which is the true and effective source of the renovating power, is made only upon the condition of the act of faith.
As soon, therefore, as God, in aid of our own unavailing efforts, takes away the remains of unbelief and gives us perfect faith in the promise, which by implication involves perfect faith in all the divine declarations, he necessarily gives us the victory. "As many as received him, to them gave he power to become the sons of God even to them THAT BELIEVE ON HIS NAME." From that memorable moment, whether our emotions are more or less strong, and whether we have had special inward signs and manifestations or not, we truly feel the purifying energy. The principle of faith, perhaps after a long inward strife, has become ascendant. We have now assumed a new position. We are now become like little children. It can now be said of us in the significant language of scripture, we are "careful for nothing" living in perfect simplicity of spirit; receiving our daily bread without disquieting thoughts of the morrow; folded and protected in the arms of infinite love.
— edited from The Interior or Hidden Life (2nd edition, 1844). Part 1, Chapter 6.