John 16:8-9:

And when he [the Holy Spirit] is come, he will reprove the world of sin, and of righteousness, and of judgment:
Of sin, because they believe not on me;

See also:

Objection: Sickness Can Be the Chastening of the Lord
Objection: Pain is God’s Megaphone to Raise a Deaf World
Mistake: Going on a Witch Hunt for Mistakes