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Does God Exist? What Are the Best Arguments?

The Short Answer

Yes, and the Catholic Church holds that this can be known by reason, not only by faith. “God, the first principle and last end of all things, can be known with certainty from the created world by the natural light of human reason” (CCC 36, quoting the First Vatican Council). The classic arguments start from plain facts about the world: that anything exists at all, that it is ordered, that we know right from wrong, and that we long for more than this world can give. Each points beyond the world to its source.

Many people today assume the opposite: that belief in God is a private feeling, a habit of upbringing, or a comfort with no evidence behind it. That is a fair question to put to believers, and it deserves a real answer.

What the Church Does and Does Not Claim

The Church does not claim:

The Church does claim that “the existence of God the Creator can be known with certainty through his works, by the light of human reason, even if this knowledge is often obscured and disfigured by error” (CCC 286).

Why Catholics Believe It

Scripture says creation points to its Maker

The Bible does not argue for God’s existence so much as assume it. But it does say that God can be known from what He has made. “Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made” (Romans 1:20). The Book of Wisdom says the same: “For from the greatness and beauty of created things comes a corresponding perception of their Creator” (Wisdom 13:5).

Why is there anything at all?

This is the deepest of the arguments, and the oldest. Everything we meet in the world is contingent: it exists, but it need not have. You might never have been born; the earth might never have formed. A contingent thing does not explain its own existence. It depends on something else, here and now.

If everything were like that, nothing would explain why anything exists at all. An endless series of borrowers, none of whom owns anything, never explains where the money came from. So there must be something that does not borrow its existence: a being that simply is, and from which everything else receives its being. That is what believers mean by God, the One who said to Moses, “I AM WHO I AM” (Exodus 3:14).

This argument does not depend on the universe having a beginning. St Thomas Aquinas thought the universe did begin, but held that this is known by faith, not proved by reason (Summa Theologiae I, q. 46, a. 2). His arguments work even for a universe that had always existed, because they ask what holds things in being now. (See What Are the Five Ways of St Thomas Aquinas?)

Why is the world ordered?

The universe runs on laws that can be written in mathematics. Scripture says God has “arranged all things by measure and number and weight” (Wisdom 11:20), and the whole of modern science rests on the bet that this is true. Things without minds act regularly and toward ends: acorns become oaks, atoms form stable elements, planets keep their orbits. Physicists also point out that many constants of nature fall within narrow ranges that allow life to exist at all. Order of this kind is what minds produce. It points to an intelligence behind nature. (See Is the Universe Fine-Tuned for Life?)

Why does right and wrong feel binding?

Almost everyone believes that some things are really wrong, not just unfashionable: torturing a child for fun, for instance. We do not feel we invented this; we feel we discovered it, and that it binds us whether we like it or not. If the universe is only matter in motion, it is hard to see where such a binding law could come from. The best explanation of a real moral law is a real source of goodness, which is God. (See Can There Be Morality Without God?)

Why do we long for more?

Human beings want things that nothing in this world fully satisfies. We reach a goal and feel strangely empty; we find beauty and ache for something beyond it. C. S. Lewis put the argument this way: “If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world” (Mere Christianity, “Hope”). St Augustine had said it fifteen centuries earlier, in a prayer: “for thou hast made us for thyself and restless is our heart until it comes to rest in thee” (Confessions I.1).

Common Objections

”Who created God, then?”

The arguments do not say that everything needs a cause. They say that everything which depends on something else needs a cause. God, by definition, depends on nothing; He does not have existence, He is existence itself. Asking what caused Him is like asking what is north of the North Pole. (See If God Created Everything, Who Created God?)

”The Big Bang shows the universe came from nothing, by itself.”

The Big Bang theory, first proposed by the Belgian priest Fr Georges Lemaître, describes how the universe developed from an early, hot, dense state. It does not tell us whether that state had a cause, or why there is a universe at all. Physicists who speak of a universe arising “from nothing” usually mean from a quantum vacuum or a set of physical laws, which is not nothing. Catholics welcome the science, but they should not overstate it. Aquinas warned against offering weak proofs for what we hold by faith, “so as to give occasion to unbelievers to laugh” (Summa Theologiae I, q. 46, a. 2). (See Does the Big Bang Prove God?)

”You can be good without believing in God.”

Of course you can, and many atheists are admirable people. The moral argument is not about whether atheists behave well. It asks what makes goodness real. The philosopher Jean-Paul Sartre was honest about this. He took as the starting point of his atheist existentialism an idea from Dostoevsky, voiced through Ivan Karamazov: that if God does not exist, everything is permitted. Most people cannot live as if that were true, and that is a clue worth following. (See Can You Be a Good Person Without God?)

”Evil and suffering show there is no good God.”

This is the most serious objection, and it deserves its own answer. (See Why Does God Allow Suffering?)

In Summary

The Catholic Church teaches that God’s existence can be known by reason. The arguments begin from things anyone can see: that things exist without having to, that the world is ordered, that right and wrong bind us, and that our hearts want more than the world gives. They do not prove the whole faith, and they do not force anyone to believe. But they show that belief in God is not a leap in the dark. And for anyone still unsure, there is one more step beyond argument: to pray, honestly, “Lord, if you are there, show me.” Many saints began exactly there.

See also What Are the Five Ways of St Thomas Aquinas?, Is Faith Irrational? and Isn’t Science the Only Real Path to Truth?

This article follows the method St Robert Bellarmine used in his Controversies*: state the question fairly, clear away misunderstandings, make the case, then answer each objection. Bellarmine also wrote a devotional book on this theme,* The Mind’s Ascent to God by the Ladder of Created Things (1615). See How We Answer Objections.

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