What is faith? I’ve seen answers that range from another religion (for example “one of many faiths”) down through some sort of fairy-tale opinion that stands opposed to science.
In the Bible, we’ll see all sorts of usage on “faith” and “belief”—sometimes even referring to when someone adheres to the doctrines that make up Christianity. One of the best usages of faith is the one that is tied to the concept of justification.
Faith is just an archaic word for trust. What I love about seeing faith, or trust, tied to justification in texts like Romans 4 (see more of the Romans study), that it explains the nature of the concept even while using, basically, case-law. No more fuzzy lessons grounded in someone’s personal trust issues, but rather taking the structure of Hebrews 11:1 where it says “faith is the substance of things hoped for; the evidence of things not seen” and garnishing it with doctrinal meat.