During much of the 19th and 20th centuries it was simply assumed among philosophers and scientists that atheism (naturalism) was obviously true and that any belief in any non-natural or god-like entities was irrational. Naturalism implied materialism and materialism entailed that there are no immaterial entities like souls, minds or God.
The universe was assumed to have had no beginning, it was infinitely old, and thus there was no need to account for an origin of space, time, matter and energy. Moreover, Darwin made it possible to explain life, it was thought, without recourse to a creator.
Everything could ultimately be explained in terms of physics and chemistry and naturalism was seen as the intelligent, educated worldview for anyone not in thrall to delusion and superstition.
It's remarkable that starting about fifty years ago all that began to change.
The universe was found to have actually had a beginning. It was also found to consist of forces, constants and other parameters that were exquisitely fine-tuned to life-permitting values. Life itself was found to be information-rich, and consciousness turned out to be inexplicable on a materialist view of life.
Philosophers, and gradually scientists, began to realize that these facts all pointed away from naturalism and toward the hypothesis that the universe and life had been intelligently engineered by a Mind.
This is not to say that everyone today is on board with this revolutionary development in philosophy and science, the intelligent engineer view is still in the minority, but it's no longer possible to say that this view is irrational, uneducated or superstitious. Indeed, it has proven itself to be extremely compelling for anyone who's not dead-set against it.
Dozens of books have been published in the last thirty years outlining the arguments for jettisoning a naturalistic worldview and adopting a theistic perspective. One of the most recent and also one of the best is a book by philosopher of science Stephen Meyer titled Return of the God Hypothesis.
The book itself may be a bit too sciency for anyone not familiar with some basic concepts in physics and chemistry, but Andrew Klavan of the Daily Wire interviewed Meyer about the book and Meyer does a good job of simplifying the argument so that any college educated and reasonably interested viewer can understand it.
The interview is twenty minutes long and can be viewed below. If you're interested in why there's dissatisfaction among philosophers and scientists with naturalism and a deepening appreciation for the greater explanatory power of theism, check it out: