The things we say and do matter as much as the things we think and feel. Understanding this concept can help us unlock the mystery of what faith really is. The apparent tension between faith and works pops up throughout both scripture and church history. Romans 10 is a passage that deals with faith in a concise and straightforward way—Paul really gets down to brass tacks:

If you confess with your mouth "Jesus is Lord" and in your heart you have faith that God raised him from the dead, you will be saved. Trusting with the heart leads to righteousness, and confessing with the mouth leads to salvation. (Romans 10:9-10 CEB)

This passage illustrates the connection between our words and our beliefs, and it can perhaps be interpreted in light of another scripture that deals with the same topic: “What fills the heart comes out of the mouth.” (Matthew 12:34 CEB)

In scripture, particularly the New Testament, the words faith and belief are often used interchangeably, and it’s important to purge any “Disneyfied” ideas about faith and belief in order to understand the biblical meaning of the words. Faith isn’t the same thing as hope, and it isn’t just mentally agreeing with certain doctrines. Real biblical faith involves your mind, emotions, and will. You exercise faith with your intellect, feelings, and actions. If any of these areas are neglected, it could be a sign of a faith that’s weak or dysfunctional.

Where did I get this definition? Well, the Bible is full of references to the human heart—and it’s obvious that it isn’t talking about the blood-pumping organ with the same name. According to Strong’s Dictionary, the Hebrew word often translated heart in the Old Testament, leb, is used to refer to “the feelings, the will and even the intellect”. The Brown-Driver-Briggs Hebrew Lexicon has a similar definition: “inner man, mind, will, heart, understanding”. (The word can also mean “the seat of emotions and passions” and “the seat of courage”.) In the New Testament, the Greek word generally translated heart is kardia, and according to Thayer’s Greek Lexicon it means “the soul or mind, as it is the fountain and seat of the thoughts, passions, desires, appetites, affections, purposes, endeavours”. A secondary definition is “the seat of the will and character”.

When I put all of that together, I come up with mind, emotions, and will. In other words, you use your heart to think, feel, and decide. And Paul says in Romans 10 that salvation depends on having faith in your heart. You exercise faith with your whole heart. And according to Matthew 12:34, if this heart faith is genuine, you’re going to talk about it.

Such a balanced, fully developed view of faith no doubt bedevils those of us who like to stress only one part of it. It’s quite tempting to oversimplify faith and make it only about doctrine, only about feelings and emotions, or only about actions. There are churches and denominations that have grown up around the particular element of faith they like to emphasize. But biblical faith must include all three.