Every book of the Bible has historical context. Someone wrote to someone else for some reason. If we can discover that context—the author, audience, and purpose—we will likely better understand the book as a whole as well as its individual parts.
According to the very first word of Romans, the apostle Paul is its author (Ro 1:1). I don’t know of any serious scholar, past or present, who has disputed this claim. Though modern scholarship loves to invent clever theories that contradict orthodoxy and long-standing church traditions, almost no one has argued anyone other than Paul wrote this epistle.
Keep in mind, however, Paul did not physically pen the words of Romans. He used a scribe by the name of Tertius. The final chapter states, “I, Tertius, who wrote this letter, greet you in the Lord” (Ro 16:22). Paul dictated the letter to him, which raises a question in my mind.
How much liberty did Tertius have as he transcribed Paul’s words? Was his recording word-for-word, or did he put Paul’s message into his own words? Regardless, I’m sure Paul had an opportunity to proofread and approve the letter before they sent it.
Though I can’t be certain, I’m inclined to believe Tertius transcribed Paul’s words as accurately as possible. The language and expressions seem much too similar to Paul’s other letters—namely, those he wrote with his own handwriting (Gal 6:11)—to think Tertius merely paraphrased Paul.