Defining faith

Faith is often said to be irrational and to involve believing in things against evidence or without evidence. But let's look at what the Bible says about faith.

Hebrews 11:1: "Now faith is being sure of what we hope for and certain of what we do not see."

2 Corinthians 5:7: "We live by faith, not by sight."

The interesting thing about these verses is that sight, which it talks about, is an unusual type of evidence. Sight is probably the most direct form of evidence that we have. There are many other forms of evidence that are not like this, such as an airplane pilot relying on their instruments rather than what they see outside the cockpit window, that is, indirect evidence.

If these verses were written with this idea in mind, if there was a specific and purposeful mention of sight-type evidence, then 'faith' in the Bible can include relying on indirect evidence.

If 'sight' excludes faith, but other forms of evidence do not exclude faith - less direct forms - then faith is extremely common. A pilot could be said to have faith in their instruments according to this definition. A person could be said to have faith in the reliability of their car, in this definition, if they haven't directly observed why their car is reliable, but rely on the engineers, salespeople, etc.

This would make Biblical faith something that is reasonable, because we rely on indirect evidence all the time, and so it would be a virtue to have Biblical faith in a lot of contexts.

Actually, this view has support when you consider how the Bible makes an argument in various places for the Christian life, God's existence, Jesus' claims, moral issues, etc (e.g. Rom 6:2, Rom 1:20, Matt 12:39-40, Rom 5:8).