Epistle to the Romans
From ReformedWiki.org, the wiki for Reformed Christianity
The Epistle to the Romans is a book in the Bible, originally written as a letter from the Apostle Paul to the Church in Rome. It is one of Paul’s most profound and theological writings, addressing key doctrines such as justification by faith, the nature of sin, the role of the law, and God’s plan for both Jews and Gentiles.