Romans, like most of the New Testament ‘letters’, is a real letter, in the sense that it was written to particular people for a particular reason – it is not (as some literary ‘letters’ were) a treatise or essay dressed up in letter form. It begins and ends with the customary greetings (though Paul always gives these a distinctive Christian content) and refers to matters that were clearly already under discussion. To understand it, we have to make some effort to reconstruct the situation, even though we do not possess the other side of the correspondence and have very limited knowledge (from Acts and from Paul's other letters) of the circumstances which caused Paul to write to a church which he had never yet been able to visit.

But this letter is also more than just a fragment of Paul's correspondence. Romans is the nearest thing we have in the New Testament to a theological treatise (apart perhaps from the letter to the Hebrews); and it is as such that it has been regarded throughout much of the history of the church, providing arguments for the protagonists in some of the most earnest debates which have taken place between churches and between believers.