Martin Luther says plainly in his preface to Romans:
This letter is truly the most important piece in the New Testament. It is purest Gospel. It is well worth a Christian’s while not only to memorize it word for word but also to occupy himself with it daily, as though it were the daily bread of the soul. It is impossible to read or to meditate on this letter too much or too well. The more one deals with it, the more precious it becomes and the better it tastes.
But he doesn’t really mean the whole book of Romans, of course. He only means chapters 3, 4, 5, 7, and 9. Romans 2 and 12 are particularly ignored in Protestantism. Protestantism takes just 5 chapters of Romans, Ephesians 2:8-9 (without the rest of Ephesians), Philippians 2:13 (without 2:12), and elevates these above the rest of Paul’s epistles even, and certainly above the gospels and the Old Testament.
Will they ever admit this? Of course not. But we don’t need them to since Martin Luther admitted it for them.
Protestantism is also heavily based on this statement from Luther in the same preface:
Sin in the Scriptures means not only external works of the body but also all those movements within us which bestir themselves and move us to do the external works, namely, the depth of the heart with all its powers.
In other words, Luther is saying the temptation equals the sin. This is Protestant harmitology in a nutshell, which is why Luther wanted to toss out the epistle of James. He kind of has to in order to make his heretical theory work!
See James 1:12, for instance:
Blessed is the man that endureth temptation: for when he is tried, he shall receive the crown of life, which the Lord hath promised to them that love him. (James 1:12 KJV)
Luther also wanted to toss out Hebrews, which makes sense for him considering how this verse demolishes his heretical definition of sin:
For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. (Hebrews 4:15 KJV)
Now, of course, the reality is that Luther’s heresy on the definition of sin can also be refuted from the Pauline epistles (the part that Luther ignores):
…God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it. (1st Corinthians 10:13 KJV)
Martin’s Luther redefinition of sin to the point where the temptation itself is a sin results in the belief that its impossible to avoid sin — ever — which is used in turn to fuel the false doctrine of total depravity. Ironically, Martin Luther says the following himself:
To begin with, we have to become familiar with the vocabulary of the letter and know what St. Paul means by the words law, sin, grace, faith, justice, flesh, spirit, etc. Otherwise there is no use in reading it.
Since Protestants continue to follow Martin Luther’s false definition of sin (not to mention Augustin’s false definition of grace, and false definitions of all these other terms besides) it is, by Martin Luther’s own admission, totally useless for Protestants to even read Romans — they can’t understand it at all.