9. ἁμαρτίας. This must come first: the work of the Spirit begins with convicting man of having rebelled against God. And the source of sin is unbelief; formerly, unbelief in God, now unbelief in His Ambassador. Not that the sin is limited to unbelief, but this is the beginning of it: ‘Because’ does not explain ‘sin,’ but ‘will convict.’ The Spirit, by bringing the fact of unbelief home to the hearts of men, shews what the nature of sin is.