Who wrote Hebrews? That is a question not easily answered. It has riddled bible scholars since the days of Origen and will likely never find an answer agreed upon by everyone. So from the outset, I will say as Origen ended up concluding that “as to who wrote the epistle, in truth, God knows.”
Generally, the popular conception is that Paul was the author, and it is to that opinion that I direct this post. William Hendricksen lists ten reasons in his Survey of the Bible why Paul was not the author. Without ado, here is his argument:
1. Hebrews is anonymous, unlike Paul’s epistles.
2. Hebrews is completely different in form from Paul’s epistles. The latter, with slight variations, follow a certain pattern—salutation followed by thanksgiving (or by doxology and thanksgiving)—which is completely absent in Hebrews.
3. About the last thing Paul would ever say is found in Hebrews 2:3: “how shall we escape if we neglect such a great salvation? It was declared at first by the Lord, and it was attested to us by those who heard (emphasis added). Paul stressed the fact that he had received his gospel from Christ (Gal. 1:11 ff.; 1 Cor. 9:1 ff. and 15:8 ff).
4. Hebrews is more calm and balanced than the usually deeply emotional style of Paul.
5. Hebrews utilizes literary Koine Greek; Paul mostly employed vernacular Koine Greek.
6. Hebrews contrasts different typologies than those usually used by Paul, such as: antitype vs. type, earthly things vs. heavenly ones; and shadow vs. reality. Paul, on the other hand, favored contrasting things like: faith and works; law and grace; and spirit and flesh.
7. The author of Hebrews quotes the LXX version of the Old Testament; Paul shows no preference for the LXX.
8. Paul loves addressing Jesus as “the Lord Jesus Christ.” The Hebrews author prefers simply calling Him “Jesus” or at most “Jesus Christ.”
9. The characteristically Pauline phrase “in Christ” does not occur in Hebrews.
10. Lastly, Hendricksen claims there are many other differences, including: Paul’s use of the term “faith” vs. the use of it in Hebrews, and Paul’s pointing his readers to imitating him as opposed to the Hebrews author pointing his readers to the Old Testament saints and others.
For me, number three is the most persuasive against Pauline authorship, as Paul was fervently adamant about Jesus giving him his gospel. Calvin also finds this aspect compelling; so toot toot for that. For me, I had never really considered the issue. I admitted we couldn’t authoritatively identify the author Hebrews, but I also always liked the idea of crediting one more epistle to Paul. Consequently, Hendricksen blew my mind with his insights (which are of course not limited to Hendricksen, as evidenced by the link to Calvin’s commentary; he was just the first source I had heard the view from).
Who then is the author? As I said in the opening, only God knows. But several suggestions have been made, including: Apollos, Priscilla, Timothy, Barnabas, Clement of Rome, or Jude, and even Luke. Among these Barnabas and Apollos appear to be the favorites, though that probably depends upon which stream of scholarship is surveyed.
In the end, what does it matter? I think knowing that Paul likely did not write Hebrews serves as another example of one the Bible's many interconnections and of God's word interpreting itself. For me, those kinds of things foster a deeper appreciation for the nuances of the Bible and testify to the one divine mind behind all of Scripture.
http://paulregent.blogspot.com/2013/02/common-bible-unknowns-author-of-hebrews.html (alyrtnative theories like apollos linked to at source)