Answer
Logic, mathematics, and philosophy all make use of axioms. In those contexts, axioms are concepts that must be accepted but cannot be proved or disproved. A simple example is that numbers equal themselves: x = x. Another is the law of non-contradiction, which says that mutually exclusive statements cannot both be true in the same sense at the same time.
No system can escape using axioms. Fundamental axioms are uniquely beyond the normal rules of logic. Instead, we define logic in relationship to those ideas and their applications. Even attempting to prove or disprove an axiom requires the use of other axioms. Denying axiomatic principles makes rational thought impossible. They “must” be believed because without them communication breaks down, and nothing can be understood.
God’s existence—the “why” of God’s being—is the axiom of our reality. God simply is because, if He were not, there wouldn’t be anything. When we ask, “Why does God exist?” or “What is the reason God exists?” we’re speaking of something that doesn’t apply to Him. Such questions attempt to apply cause-and-effect to a Being who is prior to and the source of all causes and reasons.
This means there is no reason for God’s existence. In fact, there can’t be one. Logically, His existence comes before all reasons. Asking “why” something exists implies it could possibly not exist. “Why” implies a cause leading to a result. Without the “why,” that thing would not occur. God, who has always existed and always will (Psalm 90:2), has no “why.” He must exist. When Moses asked the Lord to identify Himself, God simply said, “I AM” (Exodus 3:13–14). Jesus echoed the “I am” concept regarding His own eternal existence (John 8:58). The simplest explanation of God’s nature is that He is the Only Necessary Thing: the ultimate basis of all reality.
Critics may claim that saying, “God just exists” is a dodge, not an answer. However, it’s as valid as any other axiom. In the Christian worldview, God created everything other than Himself (Genesis 1:1; John 1:3). When we ask, “Why does 1 = 1?” or “Why can’t there be square circles?” or similar questions about logic and math axioms, we can only give that answer: they just are. Reality—let alone reason—would not exist if those axioms were untrue. We can’t provide an answer for “why” axioms are true. We can only recognize that they are true and that they must be.
In the same way, for anything to exist, there must be an always-present, causeless, necessary “something” that is not the result of anything else. There is no “why” for God’s existence; rather, He is the ultimate “why” for every other aspect of reality. God’s existence is properly axiomatic: He simply is because He must be.
