Even to this day when Moses is read [the Law], a veil covers their hearts. But whenever anyone turns to the Lord, the veil is taken away. Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom. And we, who with unveiled faces all reflect the Lord’s glory, are being transformed into his likeness with ever‑increasing glory, which comes from the Lord, who is the Spirit. (2 Cor 3:15-18 NIV84)
Spiritual truth is only revealed by the Spirit of God. Likewise, spiritual growth comes only through the work of God’s Spirit. He transforms us from the inside outward.