"However, here the Lord speaks quite differently, and says: 'The Holy Spirit will convict the world in respect of sin, because they believe not on me.' Unbelief only is mentioned here as sin, and faith is praised as suppressing and extinguishing the other sins, even the sins in the saints. Faith is so strong and overpowering that no sin dare put it under any obligation. Although sins are present in pious and believing persons, they are not imputed to them, nor shall their sins condemn them."
Sermons of Martin Luther, 8 vols., ed., John Nicholas Lenker, Grand Rapids: Baker Book House, 1983, III, p. 127. Fourth Sunday after Easter, Second Sermon John 16:5-15.