When anyone says that Christianity is not a doctrine but a life, he is setting doctrine and life in opposition to each other. This is a very perverse tendency and thoroughly characteristic of the antidoctrinal prejudice of our day. Of course according to the Bible Christianity is both a system of doctrine and a life. Moreover the doctrine and the life are organically related, and the life cannot exist and grow apart from doctrine. After all, roots are important things.

J. G. Vos, The Westminster Larger Catechism: A Commentary, 16.