God's Word is Spirit.
Romans 2:28-29 New International Version (NIV)
28 A person is not a Jew who is one only outwardly, nor is circumcision merely outward and physical. 29 No, a person is a Jew who is one inwardly; and circumcision is circumcision of the heart, by the Spirit, not by the written code. Such a person’s praise is not from other people, but from God.