Whether part of polytheistic or monotheistic systems, the concept of God is one of humanity’s oldest attempts to explain the mysteries of life. Today, however, the idea of God feels increasingly foreign, gradually fading from the consciousness of many. The gap between humans and the divine seems to grow wider, and religion appears increasingly out of place in a world dominated by scientific culture, which directs our attention to the physical, material world.

In philosophy, the question of God’s existence is a central metaphysical issue—arguably, the metaphysical issue par excellence. The term “metaphysics” derives from the Greek μετὰ [τὰ] φυσικά, meaning “beyond the physical” or “beyond nature.” Thus, metaphysics encompasses everything outside empirical knowledge—what lies beyond sensory experience.

God is traditionally described as the Supreme Being and embodiment of absolute perfection, possessing qualities like omniscience, omnipotence, and supreme goodness. If He exists, He would be a unique Entity among all beings. This Supreme Being is said to be invisible, intangible, and ultimately beyond human comprehension. He is so perfect and superior that we cannot form a clear image of Him, nor can we verify His existence through empirical means. We cannot simply point to God as we might a teapot and say, “There is God,” nor can we prove His existence in a laboratory. Consequently, many question whether something like God truly exists.

There are essentially three main stances on this question: theism, which affirms the existence of God; atheism, which denies it; and agnosticism, which holds that we should neither affirm nor deny what has not been proven by reason. Agnosticism is, in essence, a form of skepticism. Generally, skepticism is the attitude of doubting knowledge claims—whether they be opinions, beliefs, or purported facts that others accept as certain. Agnosticism, then, is a form of religious skepticism, which, according to the dictionary, is doubt concerning fundamental religious principles such as immortality, providence, revelation, or the existence of the deity.

The question of God’s existence appears to transcend human rationality to the point that, for many, belief in Him is more a matter of faith than reason. It may be that we will never be able to prove or disprove God’s existence with absolute certainty. Nonetheless, this does not absolve us from attempting to address the question rationally; history has shown that we once believed in many entities—fairies, elves, witches—that ultimately proved to be imaginary. In this book, we will examine the most significant philosophical arguments from Christian theism, skepticism, and atheism, exploring both sides of the debate on the existence of God.