Now faith is the substance of things hoped for, the evidence of things not seen. (Heb 11:1)
That word "faith" is a translation into English of a Greek word "pistis". The interesting thing about "pistis" is that in various forms it is a noun, a verb (pisteuo, pistoo) and an adjective (pistos, pistikos). There really isn't a single English word to directly translate "pistis." If you check with a concordance, you'll find that the English versions variously translate this as assurance, faith, faithful, belief, believe, believed, trust, or confidence. In the English language, all of these indicate some mental attitude or activity. They all imply something that is not "real" in the sense of not being physical and thus is something not seen. There is also the implication of something that is hoped for and not currently present. Well, that just won't do. You see, if "faith" is something hoped for and unseen, then what is stated in Hebrews 11:1 doesn't mean anything. You can see this by substituting various meanings into the sentence, like this:
"things hoped for" is the substance of things hoped for.
"things not seen" is the evidence of things not seen.
This verse in Hebrews sets out a distinction between something other than what is hoped for and unseen. Whatever the literal meaning of the original Greek word was, the way the Apostle Paul uses this word "faith" indicates he means something more than an idea in the mind.
Try this. From where you are sitting reading this, stand up. Did you notice that you did not fly off towards the ceiling? Did you even consider the possibility that you might? Before you pushed on the floor with your feet, was there any possibility in your mind that you might propel yourself skyward? No, you knew with absolute certainty that gravity would hold you to the floor. You knew it with such certainty that the idea of something else happening did not even enter you mind. What's more, you could sit there all day with the idea that gravity would hold you down if you pushed against the floor with your feet. But only when you stand up do you have evidence of that. It is the act of standing up that evidences the unseen thing we call gravity.
So there's an example of what Paul is talking about. It is an act that when performed produces the evidence of something not seen. This is "real" faith. Not real as opposed to fake. Real as in the sense of objectively demonstrated and not just an idea in the mind. We can believe something with the mind all we want, but it isn't until we act on that belief that the reality becomes evident. Paul is not talking about faith in things of this world, though. He is talking about things of God and so the faith that he speaks of is a faith in God's word. If we direct faith toward things of this world, that's different. It is when we rely on and act on God's word that we have the faith that Paul describes. The remainder of Hebrews 11 lists examples of those who did just that.
So, that covers "evidence" but how can faith also be a "substance" of something? I went and looked at a variety of lexicons and commentaries trying to get a better understanding. Unfortunately, it seems the experts can't make much sense out of this either. This Greek word translated "substance" in the King James version is hupostatis. Some say this should be translated as confidence or assurance. I don't think that makes much sense, since those are just synonyms for faith. It would be like saying, "faith is the faith of things hoped for."
Another interpretation is to use hupostatis in its literal meaning. The word is a combination of "under" and "stand on" so that a possible meaning is "foundation." Thus, "faith is the foundation of things hoped for." In this sense, faith is the substance that we build on to achieve the things hoped for.
Another interesting interpretation is based on the use of hupostatis in legal matters at the time. This word was used to indicate the legal proof of something, such as a title deed. That's somewhat better. You can say, "faith is the title-deed to things hoped for." It is a way of saying that we can claim the things hoped for by faith.
There is another very interesting use of hupostatis in the opening passage of Hebrews. Here it is in the King James translation.
[God] hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds; Who being the brightness of his glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high; (Heb 1:2-3)
That word "person" in verse two is the same Greek word, hupostasis. Some translators are more consistent and use "substance" here as well. The phrase "express image" translates a word that refers to a carving or engraving. It is a very poetic way of saying that Jesus was a physical image of God. Furthermore, that physical image was of the very power of creation of God's word. Jesus was the word of God made visible in the physical world.
I think that this is what Paul means in the first verse of chapter 11 as well. Think about this. When we act upon the word of God and God responds by fulfilling His word in us, then the truth and power of His word is put on display through our lives. This is completely consistent with the claim that faith is "evidence." When we act in complete confidence and reliance only on God's word, that eternal word is "carved" into a physically real thing. In other words, faith is not some hoped for, unseen idea. It is the means that brings the eternal, unseen power of God into reality and puts it on display. That's real faith.
The whole purpose of faith, and the ultimate purpose of man, is to be the means by which God demonstrates physically the truth and the power of His word and the glory of His person. If anything we do is of our own knowledge and will, then the glory of it would be ours. But when we accomplish things solely by faith on God's word, all the glory goes to Him. Isn't that much better than us running around trying to show off how smart and good we are? Who are we trying to kid, anyway? We cannot, by our own knowledge and will power, demonstrate true goodness of the type that God has. I think it's much better to rely in faith on the word of God, let Him fulfill His word through me, and then have Him get all the glory.