"After all, what gives us hope and joy, and what will be our proud reward and crown as we stand before our Lord Jesus when he returns? It is you!" (1 Thessalonians 2:19 NLT)
After praying about this, (what would I do next,) it was put upon my heart to share from this wonderful letter written to the church in Jerusalem; so named, "Hebrews." There is many different opinions on who wrote this Book; the strongest opinion goes towards the Apostle Paul, who would have had it written in Hebrew. There is also some indication the Luke and/or someone else translated it into Greek.
Personally, I believe that the three of them, (Paul, Mark, and Luke,) wrote it together, as they all put the entire complex picture together, as they sat together, making all these things come to life, with the power of the Holy Spirit speaking through their conversations. Why I believe this, is only because I experienced myself. Only weeks after I was saved, two brothers and I were sitting out under stars, sharing about the things God had been placing upon our hearts.
It isn't really hard to picture the three of them sharing together for hours, as they fellowshipped together where Paul was being held, whether it was a cell or under house-arrest, we know that at one point all three of them were together during Paul's detention. I imagined being a fly on the wall, as they started going through all of the things God performed and made happen; as well as those things still to come.
Anywho, it really doesn't matter, (but, then again, I think it does,) who wrote this Book; what really matter is to whom it was written and why! I have said it before, and I say it again: The whole history of Israel, all of their issues and all of their falling away, it is all a reflection of the church.
We really don't have any advantage over Israel, as some might try to say; we are the ones that get to be grafted into the people of Israel, not the other way around...
"For since their rejection meant that God offered salvation to the rest of the world, their acceptance will be even more wonderful. It will be life for those who were dead! And since Abraham and the other patriarchs were holy, their descendants will also be holy - just as the entire batch of dough is holy because the portion given as an offering is holy. For if the roots of the tree are holy, the branches will be, too. But some of these branches from Abraham's tree - some of the people of Israel - have been broken off. And you Gentiles, who were branches from a wild olive tree, have been grafted in. So now you also receive the blessing God has promised Abraham and his children, sharing in the rich nourishment from the root of God's special olive tree. But you must not brag about being grafted in to replace the branches that were broken off. You are just a branch, not the root." (Romans 11:15-18 NLT)