Because of original sin we cannot through our own efforts receive for ourselves the fruits of Christ’s work of redemption. If the Holy Spirit did not sanctify us, we would be without hope, eternally damned. For this reason God sent the Holy Spirit, so that He would create faith in Christ in our hearts, would preserve us in faith and lead us to heaven.
1 Cor. 2:14: But the natural man receiveth not the things of the Spirit of God, for they are foolishness unto him; neither can he know them, because they are spiritually discerned.
Eph. 5:8: For ye were sometimes darkness.
Eph. 2:1: Ye were dead in trespasses and sins.
Rom. 8:7: The carnal mind is enmity against God.
1 Cor. 12:3: No man can say that Jesus is the Lord, but by the Holy Ghost.
Luther says: “Therefore sanctifying is nothing else than bringing us to Christ to receive this good, to which we could not attain of ourselves.”