What is the place of the book of Hebrews, assuming Paul did write it?

What is the place of the book of Hebrews, assuming Paul did write it? Even if he did not, and assuming it does have a relatively late date, what is its purpose in light of the revelation of the mystery in Ephesians?

Brian responds:  

This is an interesting read regarding Hebrews authorship on this link http://www.bibleunderstanding.com/biblestudies.htm under "Various Subjects".

Hebrews sits perfectly in the Acts period and is in full harmony with Romans, Galatians, Corinthians and Thessalonians. Hab.2:4 is found in Hebrews 10, Romans 1, and Gals.3 and Habakkuk is about the earth;Hab 2:14  For the earth shall be filled with the knowledge of the glory of the LORD, as the waters cover the sea.

When Israel were unfaithful, (like the Acts period) the Lord made an oath the goal of which flows on through the prophets to Paul during Acts;
Num 14:21  But as truly as I live, all the earth shall be filled with the glory of the LORD.Psa 72:18  Blessed be the LORD God, the God of Israel, who only doeth wondrous things. Psa 72:19  And blessed be his glorious name for ever: and let the whole earth be filled with his glory; Amen, and Amen.Isa 11:9  They shall not hurt nor destroy in all my holy mountain: for the earth shall be full of the knowledge of the LORD, as the waters cover the sea.
Isa 11:1  And there shall come forth a rod out of the stem of Jesse, and a Branch shall grow out of his roots:Isa 11:10  And in that day there shall be a root of Jesse, which shall stand for an ensign of the people; to it shall the Gentiles seek: and his rest shall be glorious.
Rom 15:12  And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust.
Rom 15:13  Now the God of hope fill you with all joy and peace in believing, that ye may abound in hope, through the power of the Holy Ghost.

The hope of Hebrews and Romans is the realization of the oath of the Lord in Numbers 14.

Hebrews fits perfectly into this earthly redemptive theme. As Paul was a minister of the New Covenant, 2Cor.3, then Hebrews brings this forth beautifully. Paul wrote in Romans the Day was at hand, 13:11-12, the night far spent, Hebs.10 speaks from Hab., of yet a little while. Trumpets in Corinthians, Thessalonians, and Hebrews. The Day of the Lord in Thessalonians is the Day of Roms.13, and the book of Revelation. We who are alive and remain of Thessalonians are not the we of today. The seed of Abraham in Hebs.2 is in harmony with Gals.3

The writing of Hebrews might be late in the Acts period, which shows the consistency of the Acts period hope, namely that of Israel, cp Acts 26:6-7.