Most contemporary scholars, including some LDS scholars, do not believe that Paul wrote this book. It is last among the letters of Paul because those compiling the New Testament (in the early 3rd century AD) were not sure that Paul had written it. There are a variety of reasons for these doubts, but the most significant is that the language of Hebrews is quite different from that of the rest of Paul’s letters. (However, the content and occasion of the letter are also different, and that might account for the difference in language.) Notice also that, though the title traditionally given to this book is “Letter to the Hebrews,” it doesn’t have the form of a letter. Some who do not believe that Paul wrote Hebrews believe it may have been written by Apollos, one of Paul’s followers.
The book of Hebrews is what scholars call a “homiletic midrash” on Psalms 110, meaning that it a sermon responding to Psalm 110. It might be useful to read that psalm before reading Hebrews and to keep it in mind as you read Hebrews.
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