Faith is an integral part of the human experience. But faith means different things to different people. Is it simply what you believe in your mind? When it comes to faith in God, things get even more interesting.

Many people feel as if they are on a spiritual journey in life. But there are moments of doubt. And there are certainly seasons when faith in the destination is hard to come by. Some give up. Others try to persevere. Most of us eventually ask: What does it mean to put your faith in God?

It might help to distinguish between three kinds of faith. Each carries a unique connotation that can clarify the faith we desire and the barriers that sometimes stand in our way. These three kinds of faith are best described by ancient Latin words that illuminate their meaning: assensus, fiducia, and fidelitas.¹

Assensus: Faith as Belief

Assensus means “approval, assent, or agreement.”² This takes place when someone gives his or her mental assent to a proposition.

One person says, “This is the hottest summer we’ve had in a decade.” Another responds, “I believe you’re right.” By using our minds, collecting data, and making cognitive decisions, we form conclusions about what we think is true or false.

With respect to God, this kind of faith describes an individual who believes God is real and not just a figment of our imaginations. It may include other beliefs about God as well, such as: he is all-powerful, created the universe, is loving and just, hears our prayers and cares about our lives, or is described in the Bible.

But there are two barriers to faith as belief. The first is doubt, suspicion, or skepticism. Perhaps the friend in our previous example thinks she remembers a summer two years ago when it was hotter. She doubts the original statement; she does not believe it.

Many are skeptics about God’s existence for good reasons. They balk at some of the more outrageous claims in the Bible or other religious texts, or belief in God just doesn’t seem logical. But doubts need not fully exclude the possibility of faith.

We can never be 100 percent sure about anything—even our own doubts. The Bible itself tells stories about people like Thomas, one of Jesus’ own disciples, who had significant doubts but continued to make space for belief.³

Another barrier is lack of knowledge. Classical philosophers believed that knowledge and understanding must precede belief. One cannot believe the theorems of mathematics are true until one first understands them.

But many have challenged this viewpoint. Anselm of Canterbury famously wrote, “I do not seek to understand that I may believe, but I believe in order to understand.”⁴ Relatively few of us understand how speed and wings create the conditions for an enormous airplane to take flight, but all of us believe it happens thousands of times every day. Of course, we may believe because we’ve seen or experienced it. But the point remains: we do not have to understand something fully to believe it is true. 

Fiducia: Faith as Trust

In Latin, fiducia means “reliance, trust, confidence.”⁵ This is faith as trust, in which a person puts his or her trust in something or someone.

A friend builds you a chair. He carefully designs the proportions, carves the pieces of wood, and painstakingly glues them all together. You may believe it looks like a chair and should function like a chair (faith as belief), but until you actually sit down, give it your full weight, and rely on it to hold you up, you have not put your trust in the chair—or your friend’s craftsmanship. 

Faith as trust is where the rubber meets the road. It is where faith moves past mental assent and is lived out. With God, it means not simply saying that one believes he exists but trusting in that existence in such a way that one’s life is impacted.

This is the key difference between believing that something is true and believing in something. Believing in something or someone—in this case, God—is personal. It takes on a consequential dimension in our lives.

The Apostle Paul told early Christians, “If you declare with your mouth, ‘Jesus is Lord,’ and believe in your heart that God raised him from the dead, you will be saved.”⁶ It was extremely important that Christians believed that Jesus was the Messiah, had died for the sins of the world, and had been raised from the dead.

But faith was more than just assenting to these truths. One had to “declare with your mouth, ‘Jesus is Lord.’” At first glance, this does not seem like a big deal. But in the Roman Empire, where everyone had to proclaim Caesar as Lord, this was blasphemy. It was not simply unpatriotic; it was grounds for execution. For early Christians, faith in God meant trusting in him for salvation in the face of very real trials and dangers.

The barrier to this kind of faith is anxiety and worry. But, for Christians, trusting in God means not worrying about the future. Life may spin out of our control, but we trust that God is still in ultimate control. This is why Jesus told his followers:

Therefore I tell you, do not worry about your life, what you will eat or drink; or about your body, what you will wear. Is not life more than food, and the body more than clothes? Look at the birds of the air; they do not sow or reap or store away in barns, and yet your heavenly Father feeds them. Are you not much more valuable than they? Can any one of you by worrying add a single hour to your life?⁷

Fidelitas: Faith as Faithfulness

The last kind of faith is fidelitas, which means “faithfulness, fidelity.”⁸ It carries the connotation of faithfulness in a relationship to another person. The most common application of this kind of faith is in marriage. When two people get married, they pledge their love, commitment, and faithfulness to one another, forsaking all others and becoming bound to only each other.

The immediate threat to fidelity is unfaithfulness or adultery. Adultery is often the manifestation of a simple drifting apart in the relationship, usually during difficult seasons. Many of the Old Testament prophets believed this is what happened when the people of Israel drifted away from God. The prophets likened them to adulterous wives or prostitutes.⁹ But God, they asserted, would be a faithful husband who would stay by their side “in sickness and in health.”¹⁰

Things Unseen

Faith has many dimensions. And of course, it’s risky. Nothing is guaranteed. One Bible writer described faith as “confidence in what we hope for and assurance about what we do not see.”¹¹

Whether you are pursuing faith as belief, trust, or faithfulness, may you hold out hope that both the journey and destination are worth it.