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Christian theology begins with a simple but profound desire: to know God as He truly is, to understand what He has revealed, and to live in obedience to His truth. This is not merely an academic exercise or a distant philosophical inquiry. It is a personal journey into the heart of divine revelation. When theologians ask the question, “What does the whole Bible teach us today about any given topic?”, they are participating in a long and faithful tradition of seeking coherence, clarity, and unity in the Christian faith. But to answer that question rightly, one must first understand where Christian doctrine comes from, how it is developed, and which sources are allowed to shape the church’s belief and practice.
The church has always used many tools to understand God, including its own history (tradition), the created world (general revelation), and even philosophical reasoning. But despite the value of these secondary sources, Christian theology has consistently affirmed that there is only one primary source that possesses supreme authority: the canonical Scriptures of the Old and New Testaments. The Bible alone speaks as God speaks. The Bible alone reveals His perfect will with absolute reliability. The Bible alone stands above every other voice, ancient or modern.
Everything else may help us understand God, but only Scripture defines what Christians must believe.
This chapter explores why Scripture holds this unique position, how its authority is grounded in its divine nature, how theologians use additional sources responsibly, and how systematic theology organizes all of these materials into a unified understanding of Christian doctrine.
The Bible holds a place of supreme authority in Christian theology because of what it is: the very Word of God. Christian belief in the authority of Scripture rests on a foundational conviction—that all the words of Scripture are God’s words in such a way that to disobey or disbelieve Scripture is to disobey or disbelieve God Himself. The Scriptures do not merely contain God’s words; they are God’s words, breathed out by Him and preserved for His people.
The Bible makes this claim about itself repeatedly. Both the Old and New Testaments testify with one voice that the Scriptures come directly from God. In the Old Testament, the familiar phrase “Thus says the LORD” appears hundreds of times. This was not a poetic expression or a casual introduction. It functioned exactly like the opening of a royal decree in the ancient world. When a king spoke, his words carried absolute authority, demanding immediate attention and complete obedience. When the prophets said, “Thus says the LORD,” they were declaring that their message did not originate in human wisdom. Their words were not suggestions. They were divine commands.
The seriousness of this claim becomes clear when we consider the consequences for a prophet who spoke falsely. If someone claimed to speak for God but delivered a message not truly from Him, that person was guilty of false prophecy—a deadly offense. The prophets could not improvise, speculate, or inject personal opinion into the message. They were bound to speak exactly what God revealed. That same reverence for the divine word extends into the New Testament.
There, the apostolic writings openly affirm that “All Scripture is God-breathed.” This word—theopneustos—conveys a powerful image: the Scriptures originate from the very breath of God. They are spoken by Him, mediated through human authors, and recorded in written form. This means that the final written text is not just human reflection but divine revelation. It is precisely because Scripture is breathed out by God that it carries ultimate, binding authority for every Christian.
The New Testament writers also treat their own writings as Scripture. The apostolic message, grounded in the authority of Christ Himself, carries the same weight and status as the words of the Old Testament. When the New Testament quotes David and says that “the Holy Spirit spoke beforehand through the mouth of David,” it reveals something essential: when Scripture speaks, God speaks. The human authors are real, but their words are ultimately God’s words.
Because Scripture is God-breathed, theologians must treat the written Word—not hypothetical earlier versions, not imagined “sources,” and not academic reconstructions—as the final form of God’s revelation. Every word in Scripture is authoritative, reliable, and intentionally preserved by God.
If Scripture comes from God, then it must be entirely true. God does not lie. His knowledge is infinite, and His character is perfectly trustworthy. Therefore, the doctrine of inerrancy naturally flows from the doctrine of inspiration. Inerrancy teaches that the Bible, in its original manuscripts, does not affirm anything contrary to fact. Every teaching, every report, every theological claim, and every historical detail is recorded with complete truthfulness.
Some argue that Scripture is only inerrant “in matters of faith and practice,” allowing for errors in historical or scientific matters. But this distinction is foreign to Scripture itself. The Bible presents truth as a unified whole. Paul says that all Scripture is profitable for teaching, reproof, correction, and training in righteousness. Jesus affirms that God’s Word is truth. If God is the author of Scripture, then every part of His Word must be reliable.