Problem: Peter speaks in this text about “sanctification of the Spirit,” but Jesus prayed, “Sanctify them by Your truth” (John 17:17). Which way are we set apart to God—by His Spirit or by His truth?

Solution: We are sanctified through God’s truth which is from God’s Spirit. The Spirit of God is the efficient cause (that by which God works in our hearts), and the truth of God is the instrumental cause (that through which God works in our hearts). In short, God is the source, and God’s truth is the means of our sanctification.