While most people have faith in at least something (whether in God and the Bible or Allah and the Koran or Darwin and Science), how many people could give an accurate definition of what faith is? Is faith an irrational belief is something you can never prove? Do you have to park your brains to have faith? I guess it depends on how you define faith. To many, faith starts where knowledge leaves off. Mark Twain said, “Faith is believing in something you know is not true.” I'll admit, that might accurately describe some people's faith. People believe all kinds of irrational things, and sometimes even give their lives for it. But is that the nature of Biblical faith? That is, is faith as it is described in the Bible an irrational belief in something you can never prove?
The Bible itself gives us a definition of faith. In the New Testament book of Hebrews, chapter 11, we have an entire treatise on faith, beginning with a definition and then illustrated in the lives of men and women of faith from throughout Biblical history. Verse 1 says, “Now faith is the assurance of things hoped for, the conviction of things not seen” (Heb 11.1).
At its most basic level, faith has to do with that which we cannot see or have not yet obtained, and yet it is both an assurance and a conviction of the reality of those unseen things. Faith is not simply a weak wish or a leap in the dark. Though many people believe in things for no other reason than that is what they have been taught or raised with, true Biblical faith is a conviction based on sound evidence. This is seen throughout the Bible, especially in the four Gospels (Matthew, Mark, Luke, and John) and the book of Acts, the latter of which gives us the record of the early Christians as they sought to testify to their belief in Jesus and his resurrection from the dead.
The Gospels are records based on eye-witness accounts (cf. Luke 1.1-4; John 20.26-31), as is Acts (Acts 1.1-4). In Acts we see the apostles constantly reasoning from the evidence in order to persuade skeptics (Acts 2.21-36; 17.2,4,17; 18.4,19; 19.8,9,26). Their faith was based on firsthand experience, historical and eyewitness testimony, Old Testament predictions, nature, and other forms of evidence. Their faith was not unreasonable, but highly reasonable.
Nonetheless, faith by its very nature relates to “things hoped for” and “things unseen.” Thus, it relates to the unseen realities of the past, present, and future. We may have never seen the Roman Caesars, but we do not doubt they existed. We may have never seen the atomic components that hold matter together, but we do not hesitate to sit down in a chair. And we know all too well what happens when you split those components apart in an explosion. And though we have never seen Jesus in person, we can have a sure conviction that he lived and died and rose again. Enough evidence has been provided. And while we cannot see the present reality of Jesus living and ruling in heaven at the right hand of the Father, we need not doubt it because we have enough evidence. Likewise our hope (confident expectation) of eternal life beyond the grave is an unseen future lived as if it in were the present. These are all unseen, but no less real.
And yet, faith can only exist in the realm of doubt. It is not the same as absolute knowledge in terms of first hand experience. Whenever we board an airplane, we must place our complete confidence (faith) in the pilot who will fly it, the mechanics who worked on it, the engineers who designed it, and the Air Traffic Controllers who will guide it (not to mention the airport security services who protect it). Yet though we do not really know with absolute certainty that they have all done or will do their jobs correctly, we get on the plane. That is faith. But if there was no room for doubt, there would be no need for faith. As Paul said, “we walk by faith, not by sight” (2 Cor 5.7). Faith does not mean we never have doubts. It only means that we do not let doubts prevent us from acting on our faith.