Why Evolution is True

a sermon by Rev. J. Mark Worth


We will celebrate Charles Darwin’s birthday a week late. His scientific contributions changed our understanding of both biology and theology. Darwin had strong Unitarian family connections, and Unitarians and Universalists were among the first religious people to embrace his scientific findings.


  1. From Jerry A. Coyne, Why Evolution Is True, Viking, New York, NY, 2009:
    Darwin’s theory that all life was the product of evolution, and that the evolutionary process was driven largely by natural selection, has been called the greatest idea that anyone ever had. … Today scientists have as much confidence in Darwinism as they do in the existence of atoms, or in microorganisms as the cause of infectious disease.
  2. From Langdon Gilkey, Creationism On Trial: Evolution and God at Little Rock, Harper & Row, San Francisco, CA,1985:

    [Langdon Gilkey, a professor of theology at the University of Chicago Divinity School, testified at a trial regarding an Arkansas “Creation Science” law, and was asked to explain the difference between science and religion.] “Science asks how questions, questions about the character and process of change. It seeks after laws of change, and thus it concentrates on material, universal, and necessary or automatic causes, structures, laws and habits.

    “Religion asks different sorts of questions, questions about meaning. … Why is there anything at all, and why are things as they are? Why am I here, and who am I? … What is of real worth? Is there any basis for hope? What ought I to be and do? And where are we all going?

    “… It is because science is limited to a certain level of explanation that scientific and religious theories can exist side by side without excluding one another…”


Ninety-two years ago this month (Feb. 1925), the governor of Tennessee signed the Butler Act – a law outlawing the teaching of the science of evolution in Tennessee public schools. Specifically, the act prohibited “any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals.”

The American Civil Liberties Union brought a test case where John Scopes, a Tennessee high school teacher, violated the Butler Act. Attorney Clarence Darrow defended Scopes, and William Jennings Bryan, former Secretary of State and three-time Democratic presidential nominee, acted as a special prosecutor against Scopes.

The judge would not allow Darrow to call any scientists as witnesses for the defense, so Darrow put the opposing counsel, Bryan, on the stand as an expert on the Bible. Unitarian minister Charles Francis Potter helped Darrow prepare the questions. Darrow asked questions like, “Was Eve really created from Adam’s rib?” and, “If Adam and Eve were the first people, and they had sons, Cain and Able, and Cain got married – where did Cain get his wife?” Darrow used such questions to show that the Bible is not a science textbook, and should not be used as a textbook in a science classroom.

The contest between these two men seemed personal: When Darrow asked where Cain got his wife, Brian replied that he would “leave the agnostics to hunt for her.” Bryan complained that Darrow was trying to “cast ridicule on everybody who believes in the Bible.” Darrow replied that he was just trying to keep ignoramuses from teaching science. The judge announced that he considered the whole examination of Bryan to be irrelevant to the case, and that the jury should ignore the entire exchange. After eight days of trial, the jury took nine minutes to find Scopes guilty of teaching evolution. The Butler Act stayed on the books until it was challenged again in 1967.

What’s the fuss about?

In recent decades there have been continuing attempts to put forward Creationism, or its more recent incarnation, “Intelligent Design,” as a classroom alternative to the science of evolution.

Although judges in recent decades have ruled that creationism is religion and not science, about 42% of Americans tell pollsters (Gallup poll, 2014) that they believe that God created humans as they are now, and that the creation of the universe took place within the last 10,000 years. Another large group, about 31% of Americans, say that evolution took place over millions of years, but God guided the process. Only about 19% of Americans say they believe that evolution has occurred through natural selection, without divine intervention.

Science is not done by polling, of course. But they have taken a poll of scientists, too. And among scientists with academic credentials, only a little over one-tenth of one percent give credence to Creationism. The overwhelming majority of the scientific community accepts evolution as the dominant scientific theory of biological diversity.

Let’s acknowledge this fact: If we say, “In the beginning God created the heavens and the earth,” we’re making a religious statement. It cannot be a scientific statement, because the scientific method requires a testable hypothesis. Science requires observable and measurable evidence. In science you have to test your theory, measure your results, and be able to repeat the experiment and get the same results. There is no scientific test we can create that observes God, measures the capacity of God’s creative abilities, or predicts God’s future actions.

Whether you think there is a God or not, God is not a testable hypothesis. So Creationism, the idea that God created the universe, is a religious doctrine, not a scientific theory. The same is true of “Intelligent Design.” If you drop the word “God” and replace it with “designer”– as in, “an intelligent designer created the universe” – it’s just God by another name. It’s still not a testable hypothesis.
In a science classroom in a public school we must not teach religion and call it science. That would misinform our children about what science is and is not, and put American students at an educational disadvantage in a competitive world.

I’m all for teaching religion. We should teach religion in homes and in our synagogues and churches and mosques. And I think it’s a good idea to teach about religion in an elective class on comparative religions. But let’s not misinform students by teaching religion in a science class.

How does evolution work?

So what is evolution, and why does it work? Charles Darwin, who was born 212 years ago last Sunday, based his theory of natural selection on two fundamental insights – on the one hand, all living creatures are related to each other by common descent; on the other, organisms adapt to the ever- changing conditions of their world.

Here’s how evolution works: 1) species are fertile – they tend to have more offspring than survive to adulthood. 2) Populations remain roughly the same size, with small changes. 3) Food resources are limited. 4) Therefore, a struggle for survival ensues. 5) In sexually reproducing species, generally no two individuals are identical. 6) Some of these variations directly impact on the ability of an individual to survive in a given environment. 7) Much of this variation is inheritable. 8) Individuals less suited to the environment are less likely to survive and reproduce. 9) The individuals that reproduce are most likely to leave their inheritable characteristics to future generations. And 10) This gradual process results in populations that adapt to their environment over time, and after many generations these variations accumulate to form new varieties and ultimately, new species.

There’s a beautiful logic to Darwin’s theory. Those organisms that are best able to adapt will survive, reproduce, and pass on their characteristics. It is not necessarily the strong that survive, but the best adapted. Plants that are good at photosynthesis, or that have seeds that are carried to other places by the wind or by animals; bugs with protective coloring, finches with a certain shape to their beaks, antelope that are swift on their feet, porcupines that develop defensive quills, turtles with their shells, apes with large brains and opposable thumbs – we could make an endless list of adaptations.

In an okay but somewhat forgettable 2006 movie, “Man of the Year,” actor Robin Williams portrayed an unlikely presidential candidate who was asked in a debate whether he believed in
intelligent design. In one of his better lines he responded, “People say intelligent design – we must teach intelligent design. Look at the human body; is that intelligent? You have a waste processing plant next to a recreation area!”

And in the movie “Oh, God!”, George Burns, playing the role of God, admits that he made some mistakes. “The avocado, for instance,” he says. “If I had it to do over, I wouldn’t make the pit so big.”

Scientist Jerry A. Coyne comments that although organisms appear designed to fit their natural environments, the idea of perfect design is an illusion. Every species, he says, is imperfect in many ways. Kiwis have useless wings, whales have a vestigal pelvis, and our appendix is a “nefarious organ.” If organisms had been built from scratch by a perfect and all-knowing God, we would not have these imperfections. “Imperfect design is the mark of evolution;” he says, “in fact it is precisely what we would expect from evolution. We’ve learned that evolution doesn’t start from scratch. New parts evolve from old ones, and have to work well with the parts that have already evolved.” Because of this process, we should expect just the kinds of imperfections that, in fact, exist. “Some features work pretty well, but not as well as they might, or some features – like the kiwi wing – that don’t work at all, are evolutionary leftovers.”

The skeptics ~

When Darwin first presented his theory – and yes it’s a theory, just like gravity is a theory, yet we don’t all fall off the planet into outer space – when Darwin first proposed his explanation of how evolution works, many scientists remained skeptical. But as time passed the evidence in favor of Darwin’s theory continued to accumulate, and the scientists became convinced that Darwin was right.

The fossil record was just starting to be understood in Darwin’s day. When Darwin wrote On the Origin of Species in 1859, the oldest known animal fossils were from the Cambrian Period, about 540 million years ago. The absence of older fossils worried Darwin, but he expressed the confidence that older fossils would be found. Since Darwin’s time the fossil record has been pushed back to between 2.3 and 5.4 billion years before the present. The fossil record clearly demonstrates life’s evolution that has unfolded over billions of years, and demonstrates that Darwin was correct.

And Darwin didn’t know about genetics. The science of genetics, which explains how organisms inherit their characteristics, wasn’t understood until the 20th century. In the 1950s scientists demonstrated that DNA was the genetic material that determines inheritance. The science of genetics provides further proof that Darwin was right.

And we have seen evolution at work in our own time. One well-known example of natural selection in action is the development of antibiotic resistance in microorganisms. Since the first use of penicillin in 1928, populations of bacteria have evolved to become resistant to antibiotics. The microorganisms that are able to survive the antibiotic treatment become a stronger, drug-resistant strain. We have to keep developing new antibiotics as the microorganisms continue to evolve in response to drugs.
According to the University of Chicago’s Prof. Jerry A. Coyne, “Today scientists have as much confidence in Darwinism as they do in the existence of atoms, or in microorganisms as the cause of infectious disease.”

Evolution and religious faith ~

Many Christians have no problem with belief in God on the one hand, and an acceptance of science on the other – like the ancient age of the universe; the ancient geologic age of the earth; the science of genetics and DNA; the fossil record; and the biological evolution of species.

In fact, the Bible does not pretend to be a science textbook. Science asks how things happen, religion asks about the ultimate why. Science and religion give different answers because they ask different kinds of questions. Science doesn’t ask, “Should I love my enemy?” or “Am I my brother’s keeper?” Those are the kinds of questions religion and philosophy ask.

Many people reject scientific findings because they have locked themselves into a literal interpretation of the Bible. They’ve become convinced that an absolutely literal interpretation of the Bible is the only valid interpretation. But the fact is that there is no record that anyone, during the first 1600 years of Christianity, ever said that the Bible must be taken absolutely literally. And almost no one said that until the late 1800s or the early 1900s. Hard literalism, the idea that everything in the Bible must be taken absolutely literally, is a relatively modern idea. It’s not that old-time religion, it’s a recent idea.

The Bible contains parables, poetry, proverbs, testimonies of faith, visions, philosophy, history – and yes, mythology – and throughout most of Christian history much of it has been understood symbolically or metaphorically. My father, who was a Methodist minister, looked at 2 Peter 3:8 which declares, “with the Lord one day is like a thousand years and an thousand years are like one day.” So he found no need to take the “six days” of creation in Genesis literally. He said, “If the Bible doesn’t take ‘days’ literally, I don’t have to, either.”

I don’t find evolution to be anti-religious. Rather, I’m inspired by knowing that all living things are related. We are not separate from this world. We were not just plunked down on earth, unconnected and unrelated to the plants and animals around us. To the contrary, all living things are interconnected! Our seventh Unitarian Universalist principle affirms “respect for the interdependent web of existence of which we are a part.” I find that profoundly religious, profoundly spiritual.
Evolution teaches us that we are all interconnected. We all share the same Spirit of Life. Creatures that seem different are not so different. We are brothers and sisters in one big, diverse living family – we are related to all of humanity, and are cousins to all other living things. So it is high time that we learn to get along, to live in peace with one another, and live in harmony with our environment. We are not overlords of this planet who can exploit the Earth’s resources and pollute the air and water without reaping the consequences. We need to be good stewards, for we have only one planet, and when it is gone, we are gone.

Evolution also teaches us that diversity is not a bad thing. Things change. Time does not stand still, and neither does life. Diversity and change lead to a deeper and more developed life. When people or nations or religions try to stop things from changing, they are bound to fail.
We know that matter and energy are interrelated. Matter is neither created nor destroyed – energy can become matter, and matter can become energy, but they are not destroyed. Thus, our bodies and the stars are made from the same elements, and come from the same Source. The Oneness of everything is part of my understanding of God. To me, the Creative Process of the Cosmos is my shorthand definition of God. We are one with the Cosmos, and everything in it. Ecology and conservation ought to be, therefore, religious practices. In her song, “Woodstock,” Joni Mitchell links science and religion. She put it this way: “We are stardust, we are golden, we are billion-year-old carbon; and we’ve got to get ourselves back to the Garden.”

The twentieth century British biologist Julian Huxley said, “We are the universe becoming conscious of itself.” Through us, for the first time, the universe has developed a consciousness that is becoming aware of this diversity, this interrelatedness, and the responsibility that comes with it. Encoded in our DNA is the stuff of stars. Our future, I believe, depends on our ability to comprehend and act on our interdependence with all life. That is a religious responsibility and a spiritual task.