Materialism says that the only thing that can be shown to exist is matter, and that the entire universe can be explained in strictly physical terms. Many atheists and modern philosophers are materialists…that is, they reject the notion that anything non-physical exists.
The second law of thermodynamics, however, proves them wrong. Simply stated, “The entropy of the universe tends to a maximum”. Left alone, the universe’s energy would go from being unevenly distributed (as stars, for example) to being evenly distributed. The average temperature in the universe would approach Absolute Zero. At that point, no physical actions or reactions would be possible. This principle of entropy tells us that the universe had a beginning, and that it’s ‘running down’.
That the universe had a beginning isn’t news to most of us. We’re familiar with the Biblical account of God’s creation of the universe, or – for our non-religious friends – with the non-religious Big Bang. Interestingly, many secular scientists had a serious problem with the Big Bang. Because it suggests that the universe has a beginning, many cosmologists in the 1920’s and 1930’s reacted strongly to what they considered an injection of religion into their work. They preferred to believe that the universe is eternal. Nonetheless, most agree at this point that some Big Bang must have occurred.
Because the universe had a beginning, we must ask the question “what caused the universe to be?”. Cosmology, of course, can’t address this question today. Philosophy, however, gives us some insight. Because the universe can’t have caused its own existence, something outside the universe has to be its cause. Because the universe hasn’t reached heat death, it’s not eternal. Because the universe couldn’t create itself, there is something outside the universe. Now, it’s a huge leap from that to God, but it’s a start…and it’s an answer to the strict materialism that often gets promoted in opposition to any sort of supernaturalism.