According to your faith
To this confidence, that God is both able and willing to sanctify us now, there needs to be added one thing more: a divine evidence and conviction that he does it. In that hour it is done. God says to the inmost soul: According to your faith, be it to you (Matthew 9:29)! Then the soul is pure from every spot of sin; it is clean from all unrighteousness (1 John 1:9). The believer then experiences the deep meaning of those solemn words: If we walk in the light as he is in the light, we have fellowship with one another, and the blood of Jesus Christ his Son cleanses us from all sin (1 John 1:7).
1771 text
17. To this confidence, That God is both able and willing to sanctify us now, there needs to be added one thing more, a divine evidence and conviction, That he doth it. In that hour it is done. God says to the inmost soul, According to thy faith, be it unto thee! Then the soul is pure from every spot of sin; it is clean from all unrighteousness. The believer then experiences the deep meaning of those solemn words, If we walk in the light as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.