So the issue is not resolved by simply choosing a specific English translation. In the choice of substance vs. assurance the waters are further muddied by the fact that the Greek word we are seeking to understand, hupostasis , is a term used by Greek philosophers. So on the basis of the words of this passage alone, there are questions that cannot be answered unless we examine the context. There is something important to be learned even if we have not determined the exact meaning of some of the words. Because there is only one verb at the beginning of this passage, is, we know that we are speaking of two aspects of the same thing, not two distinct things that faith may be.
True faith involves both the present and the future.
The author of Hebrews expected that his readers would be familiar with this writing, weaving it into his discussion in chapter 10. Habakkuk lived about six hundred years before Christ. The military power of the Babylonian empire was growing. The prophet Jeremiah, author of the book of Jeremiah, was a contemporary. The Assyrians destroyed the nation of Israel about a hundred years before.