The Fifth Way we can know that God is real!
© 2021 Patrick C. Marks, All rights reserved
The following is a preview from the FAQ section of my new book…
The Bible says that every human being has no excuse to think God does not exist. Romans 1:19 says this is the case because what we can know about God is clear from what exists in the universe. How things are and how they must have come into being in the first place not only shows that God is real but also shows what the true God must be like. Nearly 800 years ago, a philosopher named Thomas Aquinas wrote about how Romans 1:19 works in the real world. His ideas are often called “The Five Ways.”
Aquinas’s Fifth Way is about why things in the universe act the way they do. For example, in nature, natural things, such as protons and electrons, act a certain way, but by themselves they have no ability to decide to act in any way. Protons, for example, do not think or decide to act like protons. Electrons do not choose to be attracted to protons – that is simply the way electrons act - it is what electrons do. But how did protons and electrons come into existence with just the right attractions built in, from the start, without the protons or the electrons deciding anything? Of course, without protons and electrons acting as they do, nothing material in this universe could exist because every material thing is made of protons, neutrons, and electrons.
Without an intelligent cause to make protons and electrons act just the right way, there is no way to explain why they act exactly as they must. There is no way to explain why, for example, an electron has the natural attraction it does to act for an end that is good, such as being attracted to a proton. The universe itself is held together by natural laws, but natural laws such as the law of gravitation or the strong and weak nuclear force, do not have a mind. Natural laws are not things or persons. Natural laws are just descriptions of how things operate so there must be a mind outside the laws of the universe that made the universe the laws describe act exactly as the universe needed to work.
Asking why an electron is attracted to a proton or why any natural law exists as it does, strongly suggests there is an intelligent cause. This is true because every effect (and every law) that begins to exist must have a cause. But since there must be a cause for natural laws and natural attractions, this cause made the natural law or attraction to act as it “should.” Any time you are dealing with a “should” you are implying there is a right way “things should exist.” The Fifth Way implies not only God as the uncaused, intelligent efficient cause of the universe but the Fifth Way also explains that God must be moral. This is so because whatever is moral is whatever relates to right conduct. What is moral is whatever defines what is right versus what is wrong. Since the Creator made natural laws and natural attractions in the universe that act the way they “should,” then it follows that the Creator (God) defines what is right and wrong in the universe. Dr. Norman Geisler says, “if anyone insists there is a real imperfection in the world, then there must be a perfect standard by which this is known.”  This is what the Fifth Way explains.
Since morality is what is good as opposed to what is bad, and God is the pure source of morality and pure perfection, then God is not just good – He is goodness itself in a pure sense. Aquinas explained that since God is goodness itself, then anything else that we call “good” is only good because it resembles God’s goodness in some imperfect way.
Another way to see this is to think about human behavior. Throughout human history, and in every culture on earth, there are standards and ways of life that everyone believes are the normal ways people “should” act. There are different ways people think everyone should act, but nothing like a totally different way. C.S. Lewis said that one culture may differ from another in terms of what one culture says is adultery and what is not, but every culture has some idea that the culture calls adultery. Lewis goes on to explain that moral laws like this cannot be explained away as just animal-like instinct because time-after-time, humans will ignore a strong instinct (such as the instinct to survive) for a higher moral reason (such as risking your own life to save a drowning person). He also showed that moral laws cannot be just a cultural thing either because too many ideas about how people “should” act go against what is socially popular. And finally, Lewis said that moral laws cannot just be preferences because human beings cannot get rid of the idea of morality no matter how hard some people have tried. C.S. Lewis put it this way,
My argument against God was that the universe seemed so cruel and unjust. But how had I got this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line. What was I comparing this universe with when I called it unjust? If the whole show was bad and senseless from A to Z, so to speak, why did I, who was supposed to be part of the show, find myself in such violent reaction against it? 
“The Fifth Way says natural things have an attraction, it can’t be by chance, so God built in this action.”
Natural things, such as protons and electrons, act a certain way, but by themselves they have no capacity to decide to act in any way. Without an intelligent cause there is no way to explain why, for example, an electron has the natural inclination of being attracted to a proton. Natural laws are not the answer to this question because a natural law is just a description of how things act, but the natural itself does not have a mind to direct the action of the law. There must, therefore, be a mind outside the laws of the universe which governs the workings of the laws themselves.
In addition, by asking why an electron is attracted to a proton there is an implied answer that the electron is simply acting as it “should.” But if there is a “should” in the universe, then there must be a mind to decide how anything “should” be. The Fifth Way explains that not only is God the uncaused, efficient cause of the universe but God is moral because He has designed the universe to act in a specific way toward ends that are good. Since there is goodness in the world but it is imperfect, then God must be the perfect source of all Goodness. This means that God is goodness itself.
Thomas Aquinas wrote,
“We see that things which lack intelligence, such as natural bodies, act for an end…to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence…therefore some intelligent being exists by whom all natural things are directed to their end.” 
 Norman L. Geisler, Baker Encyclopedia of Christian Apologetics, (Grand Rapids, MI: Baker Books, 1999), 500.  C.S. Lewis, Mere Christianity, (New York, NY: HarperCollins Books, 1952, 1972), 38.  Aquinas, Summa Theologica, 14.