Epistle to the Romans

The Epistle to the Romans or Letter to the Romans, often shortened to Romans, is the sixth book in the New Testament. Biblical scholars agree that it was composed by the Apostle Paul to explain that salvation is offered through the gospel of Jesus Christ. It is the longest of the Pauline epistles and is often considered his "most important theological legacy" and magnum opus.

In the opinion of Jesuit scholar Joseph Fitzmyer, the book "overwhelms the reader by the density and sublimity of the topic with which it deals, the gospel of the justification and salvation of Jew and Greek alike by the grace of God through faith in Jesus Christ, revealing the uprightness and love of God the Father."

N. T. Wright notes that Romans is

...neither a systematic theology nor a summary of Paul's lifework, but it is by common consent his masterpiece. It dwarfs most of his other writings, an Alpine peak towering over hills and villages. Not all onlookers have viewed it in the same light or from the same angle, and their snapshots and paintings of it are sometimes remarkably unalike. Not all climbers have taken the same route up its sheer sides, and there is frequent disagreement on the best approach. What nobody doubts is that we are here dealing with a work of massive substance, presenting a formidable intellectual challenge while offering a breathtaking theological and spiritual vision.

The scholarly consensus is that Paul authored the Epistle to the Romans.

C. E. B. Cranfield, in the introduction to his commentary on Romans, says:

The denial of Paul's authorship of Romans by such critics ... is now rightly relegated to a place among the curiosities of NT scholarship. Today no responsible criticism disputes its Pauline origin. The evidence of its use in the Apostolic Fathers is clear, and before the end of the second century it is listed and cited as Paul's. Every extant early list of NT books includes it among his letters. The external evidence of authenticity could indeed hardly be stronger; and it is altogether borne out by the internal evidence, linguistic, stylistic, literary, historical and theological.

...
Wikipedia