George Leo Haydock

Now the Lord is a Spirit. Many expound it, the Spirit is the Lord. And where this Lord and this Spirit is, there is liberty; i.e. by this Spirit, they who are sanctified are freed from the slavery of sin and the devil. (Witham) — We must recollect what he had said before, that the letter killeth and that the Spirit giveth life; that by the Spirit was meant the gospel, and by the letter was meant the law of Moses. Here he says that God is the Spirit, in opposition to the law of Moses; that he is the Author of the liberty of the children of God, in the new law; that in the new law are found the true adorers in spirit and truth, in opposition to the spirit of servitude which animated the Jews. (Calmet)