What Is the Act of Faith? Assent, Certainty, Doubt and the Gift of Belief

Going Deeper

The common objection that faith means “believing without evidence” is answered in Is Faith Irrational?, and a simple introduction is given in What Is Faith? This article goes a step further and asks what faith actually is as an act of the human person.

Faith Rests on a Witness

Most of what any of us knows, we know by trusting others. You believe that Australia exists, that your great-grandparents lived, that the earth orbits the sun. Very few people have verified these things for themselves. They believe them on the word of reliable witnesses. Theologians call this kind of knowledge belief in the strict sense: assent to something on the authority of another.

Christian faith has this structure, but with a unique witness. The Catechism defines faith as “a personal adherence of the whole man to God who reveals Himself” (CCC 176). It is first of all trust in a person, God, and then belief in what He has revealed because He has revealed it.

The First Vatican Council taught that the motive of faith is “the authority of God Himself who reveals, who can neither deceive nor be deceived” (Dei Filius 3; CCC 156). We do not believe the articles of the Creed because we have proved them. We believe them because God has said them, and God is the most reliable witness there could be.

Two Sides of Faith

The Catechism describes faith as both a personal adherence to God and a free assent to the whole truth He has revealed (CCC 150). The two belong together. You cannot truly trust a person while refusing to believe what he tells you.

St Thomas Aquinas analysed the act of faith carefully. It is an act of the intellect, which assents to a truth. But the intellect is moved to assent by the will, because the truths of faith are not self-evident or proved. And the will is moved by grace (Summa Theologiae II–II, q. 2, a. 9). So faith involves the whole person: mind, will and God’s help together.

Is There Evidence?

If faith rests on God’s word, does evidence play any part? Yes, but in a particular way.

The Church teaches that God has given motives of credibility: signs that make it reasonable to believe that He has spoken. The Catechism lists the miracles of Christ and the saints, prophecies, the Church’s growth and holiness, and her fruitfulness and stability (CCC 156). These signs do not prove the content of faith, such as the Trinity. They show that believing is the reasonable response to a God who has given good reason to trust Him.

A good comparison is a marriage. A woman cannot prove scientifically that her husband loves her. But she has many signs of his love, and on that basis she trusts him. Her trust is not blind. Nor is it mere calculation. It is a personal commitment based on good reasons, going beyond what the reasons alone could prove.

How Can Faith Be Certain?

Here is a striking claim. The Church teaches that faith is more certain than any human knowledge, “because it is founded on the very word of God who cannot lie” (CCC 157).

This can sound arrogant. But it follows from what faith is. The certainty of a belief depends on the reliability of its source. If the source is God, the certainty is the highest possible. It is not the certainty of a proof that we can check for ourselves. It is the certainty of a word that cannot fail.

The Catechism adds honestly that the truths of faith “can seem obscure to human reason and experience.” Faith is certain in its source, though often dim in our understanding.

Faith and Doubt

What about doubt? Many believers feel uncertain at times and wonder if they have lost their faith.

St John Henry Newman made a famous distinction: “Ten thousand difficulties do not make one doubt.” A difficulty is a question we cannot yet answer, or a truth we find hard to understand. Every thinking believer has difficulties. A doubt, in the strict sense, is a deliberate withholding of assent: deciding not to believe. Difficulties are compatible with faith. Indeed, faith seeks understanding precisely because it has questions.

Feelings are another matter. Faith is not a feeling. A person may feel nothing in prayer, or feel that God is absent, and still have strong faith. Some of the greatest saints, such as St Thérèse of Lisieux and St Teresa of Calcutta, lived through long periods of darkness in which they felt no consolation at all, while continuing to believe and to act on their faith.

Faith Is a Gift

The Church teaches that faith is a gift of God, a supernatural virtue infused by Him (CCC 153). When St Peter confessed that Jesus is the Christ, Jesus replied, “flesh and blood has not revealed this to you, but My Father who is in heaven” (Matthew 16:17).

This does not make faith any less human. The Catechism insists that believing is “an authentically human act,” contrary neither to freedom nor to reason (CCC 154). God’s grace does not override our mind and will; it enables them.

Faith That Lives

Finally, faith is not mere belief in propositions. St James warns that “faith apart from works is dead” (James 2:26), and even demons believe that God exists (James 2:19). Living faith is faith “working through love” (Galatians 5:6).

Faith is the beginning of eternal life. It is the way we first hold on to God, before we see Him face to face. As St Paul puts it, “now we see in a mirror dimly, but then face to face” (1 Corinthians 13:12).