"Now faith is being sure of what we hope for, and certain of what we do not see." Those were the words of the author of the Book of Hebrews. The temptation was strong amongst the Jews that they keep their faith, that they hold on to the traditions and rituals of their fathers
The author, due to the circumstances of his serious study of the Bible, and opportunities to teach it for now over 50 years, has long regarded it as his favorite book of the Bible, and the one that he's studied the most. At this stage of life, it now rings similar to Matthew, Peter's epistles, Revelation, and James, all written about the same time, all dealing with the persecution of Christians by unbelieving Jews, all dealing with an imminent judgment coming on Old Covenant Israel, and all dealing with the passing away of old heaven and earth, AND the inauguration of the new heavens and earth. These are topics which he's researched extensively in his latest books.