Legalism lacks the supreme sense of worship. It obeys but it does not adore.
Geerhardus Vos
It may be briefly pointed out how in the Reformed theology the same great perceptions lie embedded that we have found shaping the doctrine of the epistle. The first place should be given to the recognition of the majesty and sovereignty of God in the whole process of religion and redemption. It is all embraced in a διαθήκη, a comprehensive system, and in this system all things are of God. His is the originality in conceiving, His the initiative in inaugurating, His the monergism in carrying out. There is no room for any fortuitousness of chance, any uncertainty of issue, no point anywhere where the hand of God is not in absolute control. It is a system that has an oath of God and a sponsorship of Christ back of all its provisions. And the principle thus recognized in the redemptive sphere also asserts itself in the general religious attitude of man towards God. A deep impression of the divine majesty colors all intercourse with Him. For Him are all things and through Him are all things. The creature exists for His sake. He is the living God into whose hands it is fearful to fall, for those who disobey Him a consuming fire. A consciousness of strict accountability in view of God’s sovereign rights over man has always characterized the Reformed religion, even to such an extent as to invite the charge that its puritanic practice savors of a spirit of legalism more at home in the Old Testament than in the New. But legalism has nothing to do with this; it is here as in Hebrews simply the correlate in life of the vivid impression of the majesty of God in belief. Legalism lacks the supreme sense of worship. It obeys but it does not adore. And no deeper notes of adoration have ever been struck than those inspired by the Reformed faith, no finer fruit of the lips making confession to God’s name has ever been placed upon the Christian altar.
Vos, G. (2001). Redemptive History and Biblical Interpretation: The Shorter Writings of Geerhardus Vos. (R. B. Gaffin Jr., Ed.) (pp. 231–232). Phillipsburg, NJ: P&R Publishing.