6. The Epistle to the Romans is the first of all, not with respect to writing, but with respect to dignity. To the Ancients it was reputed as the Catechism of Christians.
The Epistle to the Romans obtains the first place, not indeed with respect to the time of writing, but by reason of dignity.For it was written to the faithful of Rome, that is, the inhabitants of that city, which obtained the highest Majesty in the world at that time, and gave laws to the earth:but concerning the primary articles of the faith it treats so compendiously and skillfully that it is with good reason said to contain the marrow, and a choice summary, of all Theology, and among the ancients goes under the name of the Catechism of Christians.
Dr. Dilday's Lecture: "Romans, Part 1"