"Zacharias and Elizabeth were godly folk, careful to obey all of God's laws in spirit as well as in letter." Luke 1:6

To obey "in spirit" means that what was obeyed came from the heart of love and reverence for God, not just some habitual practice with no meaning or passion behind it. Out of love for God and faith in Him, "godly folk" don't find it hard to follow the "letter" of the law, "as it is written," because the law is no longer restricting, it is now life-giving guidance and direction, correction and reproof. The Law has now become a tutor, preparing us for Kingdom life, welcomed and adhered to. Traditionally, a young heir had to have a tutor until his father determined he was ready to handle the affairs of the family. An heir then was little better than a slave. But Christ's coming changed that. Because what the Law could not accomplish in maturing the son, the Father completed by His Spirit--the Spirit of Christ infused in us, His children and heirs. The Law is now "written on their hearts" (Jeremiah 31:33). Think about it.