Deuteronomy 18:21

KJV

And if thou say in thine heart, How shall we know the word which the LORD hath not spoken?

KJV (with Strong's)

And if thou say {H559} in thine heart {H3824}, How shall we know {H3045} the word {H1697} which the LORD {H3068} hath not spoken {H1696}?

Complete Jewish Bible

You may be wondering, 'How are we to know if a word has not been spoken by ADONAI?'

Berean Standard Bible

You may ask in your heart, “How can we recognize a message that the LORD has not spoken?”

American Standard Version

And if thou say in thy heart, How shall we know the word which Jehovah hath not spoken?

Commentary

### SUMMARY
Deuteronomy 18:21 captures a profound and essential question arising from the heart of the Israelite community, immediately following God's severe warnings against the dangers of false prophecy and the foundational promise of a true prophet. This verse articulates the people's legitimate and pressing concern: "How can we, as God's covenant people, reliably discern the authentic word spoken by the LORD from a deceptive, presumptuous, or humanly contrived utterance?" It highlights the deep-seated need for a clear, verifiable methodology to distinguish divine truth, thereby setting the crucial stage for God's immediate and practical answer provided in the subsequent verse.

### CONTEXT
* **Literary Context:** Deuteronomy 18:21 is strategically positioned within a significant block of Mosaic law (chapters 12-26) that details the statutes and ordinances for Israel's life in the Promised Land. More specifically, chapter 18 is dedicated to establishing the proper channels of divine revelation, sharply contrasting them with the abhorrent pagan practices prevalent in the surrounding nations. The preceding verses, particularly [Deuteronomy 18:9-14](/deuteronomy/18-9-14 "Deuteronomy 18:9-14 - Warning Against Abominable Practices"), issue stern prohibitions against detestable acts such as divination, sorcery, necromancy, and consulting mediums, which characterized Canaanite worship. In stark opposition to these forbidden practices, [Deuteronomy 18:15-19](/deuteronomy/18-15-19 "Deuteronomy 18:15-19 - The Promise of a Prophet Like Moses") introduces the momentous promise of a future prophet "like Moses," through whom the LORD Himself would speak directly to His people. This divine provision is immediately followed by a grave warning in [Deuteronomy 18:20](/deuteronomy/18-20 "Deuteronomy 18:20 - Warning Against Presumptuous Prophets") against any prophet who dares to speak a word in the LORD's name without His command, or who presumes to speak in the name of other gods. Verse 21 then naturally emerges as the people's anticipated, practical, and internal question, recognizing the vital necessity for a clear test of prophetic authenticity, which God graciously provides in [Deuteronomy 18:22](/deuteronomy/18-22 "Deuteronomy 18:22 - The Test of a True Prophet").
* **Historical & Cultural Context:** The ancient Near East was a complex tapestry of religious beliefs and practices, many of which centered on attempts to gain insight into the future or manipulate spiritual forces through various forms of magic, omens, and communication with the dead. The Canaanites, whom Israel was commanded to dispossess, were deeply immersed in such abominable rituals, including child sacrifice, consulting mediums, and various forms of sorcery. Against this pervasive backdrop, God meticulously established Israel as a distinct, holy nation with a unique covenant relationship, where direct, authoritative communication would come exclusively through His chosen prophets, not through pagan divination or human manipulation. The question articulated in [Deuteronomy 18:21](/deuteronomy/18-21 "Deuteronomy 18:21 - The People's Question of Discernment") underscores the profound practical challenge for a people surrounded by a multitude of spiritual claims to remain steadfastly devoted solely to the LORD's pure revelation. It highlights God's divine provision for Israel to maintain their spiritual purity and remain undefiled by the spiritual corruption of their neighbors, ensuring they would not become "like those nations" ([Deuteronomy 18:9](/deuteronomy/18-9 "Deuteronomy 18:9 - Do Not Be Like Those Nations")).
* **Key Themes:** This pivotal verse significantly contributes to several overarching theological and narrative themes found throughout Deuteronomy and the broader biblical canon. Foremost among these is **Divine Discernment**, emphasizing the urgent and enduring necessity for God's people to accurately distinguish between authentic divine revelation and human or demonic deception. This profound concern for spiritual purity and unwavering obedience in the face of potential false prophets is paramount to Israel's covenant fidelity. Secondly, it highlights the **Authenticity and Authority of Prophecy**, underscoring the immense gravity of prophetic ministry and the absolute requirement for its divine origin; any word spoken in the LORD's name must genuinely and exclusively originate from Him alone. Finally, the verse speaks powerfully to **God's Faithful Provision and Protection**, demonstrating His omniscience in anticipating His people's practical need for a verifiable test to safeguard them from spiritual error, false prophets, and harmful influences. This divine concern for protecting His people from deception and leading them in truth is a recurring motif throughout Scripture, powerfully echoed in the New Testament's warnings against false teachers and spirits (e.g., [Matthew 7:15](/matthew/7-15 "Matthew 7:15 - Beware of False Prophets") and [1 John 4:1](/1_john/4-1 "1 John 4:1 - Test the Spirits")).

### EXPOSITION AND ANALYSIS
#### Key Word Analysis
* **Say (Hebrew, _'âmar'_):** While commonly translated as "say" or "speak," in this specific context, particularly when paired with "in thine heart," this verb (H559) denotes an internal deliberation, a profound thought process, or a question arising from one's innermost being. It signifies not necessarily an audible utterance, but a deep, unvoiced query or a weighty concern that occupies the mind. This emphasizes the genuine, practical, and existential nature of the people's dilemma.
* **Heart (Hebrew, _lêbâb'_):** In biblical Hebrew, "heart" (H3824) is far more than merely the seat of emotions; it represents the very core of one's intellect, will, moral being, and conscience. To "say in thine heart" means to ponder deeply, to consider thoughtfully, and to raise a fundamental question of discernment from one's core understanding and sincere concern for truth and spiritual integrity. It signifies an earnest desire for clarity and divine guidance.
* **Know (Hebrew, _yâdaʻ'_):** This verb (H3045) implies a comprehensive and experiential knowledge, extending beyond mere intellectual comprehension. The people are not asking for a theoretical understanding but for a practical, tangible, and verifiable means by which they can discern, recognize, and confidently confirm the divine origin of a prophetic utterance. It suggests a process of observation, testing, and verification that leads to an unshakeable conviction regarding the authenticity of God's word.

#### Verse Breakdown
* **"And if thou say in thine heart,"**: This opening clause anticipates a natural, internal struggle or a question that will inevitably arise within the community of Israel. It acknowledges the inherent human need for certainty and clarity, especially when confronted with the grave warnings about spiritual deception. The phrase "in thine heart" underscores that this is a genuine, practical dilemma that will be pondered deeply by individuals and the community as a whole, highlighting their concern for covenant fidelity.
* **"How shall we know"**: This is the central rhetorical question of the verse, expressing the people's fundamental and urgent need for a reliable method of discernment. It functions as a plea for a clear, unambiguous, and divinely provided test to distinguish between true and false prophecy. The use of "we" emphasizes that this is a communal concern, directly impacting the entire nation's ability to faithfully follow God's will and avoid spiritual error.
* **"the word which the LORD hath not spoken?"**: This concluding clause precisely defines the object of their profound concern: identifying those words that falsely claim divine origin. It underscores the immense danger and spiritual peril of presumptuous or deceptive prophecy—utterances spoken in the LORD's name that He has not actually commanded, or words uttered under the influence of other deities. The question is fundamentally about how to protect themselves and maintain the purity of their relationship with the one true God from such dangerous spiritual counterfeits.

#### Literary Devices
Deuteronomy 18:21 masterfully employs a **Rhetorical Question** to underscore a critical theological and practical dilemma facing the Israelite community. The question, "How shall we know the word which the LORD hath not spoken?", is not posed for the people to answer themselves, but rather to skillfully set the stage for God's immediate and authoritative response in the subsequent verse ([Deuteronomy 18:22](/deuteronomy/18-22 "Deuteronomy 18:22 - The Test of a True Prophet")). This literary device brilliantly creates a palpable sense of **Anticipation**, drawing the reader into the legitimate concern of the people and building expectation for the divine solution. Furthermore, the verse implicitly utilizes **Contrast** by juxtaposing the authentic, divinely inspired word of the LORD with words "which the LORD hath not spoken," thereby emphasizing the absolute and unbridgeable distinction between divine truth and human or demonic falsehood. This powerful literary technique highlights the profound gravity of spiritual discernment and the vital importance of adhering solely to God's revealed will.

### THEOLOGICAL AND THEMATIC CONNECTIONS
Deuteronomy 18:21 profoundly illustrates God's unwavering faithfulness and His deep desire for His people to walk in truth, unburdened by deception. It reveals a compassionate God who not only anticipates the spiritual challenges His covenant people will face but also graciously provides them with clear, practical guidance. The question posed by the people reflects a mature theological understanding that God's word is singular, intrinsically authoritative, and fundamentally distinct from any humanly contrived or pagan utterance. It underscores the foundational principle that true prophecy must originate solely and exclusively from the LORD, emphasizing His absolute sovereignty over all revelation. This verse also highlights the enduring human responsibility to exercise diligent discernment, not blindly accepting all claims to truth but diligently testing them against established divine standards. The integrity of God's communication is paramount to the covenant relationship, and His provision of a verifiable test ensures that His people can confidently distinguish His authentic voice, fostering a relationship built on unwavering trust and divine truth.

* [Matthew 7:15](/matthew/7-15 "Matthew 7:15 - Beware of False Prophets")
* [1 John 4:1](/1_john/4-1 "1 John 4:1 - Test the Spirits")
* [Acts 17:11](/acts/17-11 "Acts 17:11 - The Bereans Tested the Scriptures")

### REFLECTION AND APPLICATION
The timeless principle embedded in Deuteronomy 18:21 remains profoundly relevant and critically important for believers in every generation, especially today. In an era characterized by an overwhelming abundance of information, a proliferation of diverse spiritual claims, and a cacophony of competing voices, the urgent need for discerning God's true word is more pressing than ever before. We are called to cultivate a spirit of discerning wisdom, not born of cynical suspicion, but from a deep, unwavering commitment to truth and an absolute reliance on the guidance of the Holy Spirit. This involves diligently testing all teachings, prophecies, spiritual claims, and even personal impressions against the unchanging and infallible standard of God's revealed Word, the Bible. Just as ancient Israel desperately needed a verifiable method to identify true prophets and avoid deception, believers today must carefully and prayerfully examine what they hear and read, ensuring it aligns perfectly with the holy character of God, the transformative teachings of Christ, and the consistent, unified message of Scripture. This commitment to rigorous discernment protects us from spiritual error, strengthens the very foundations of our faith, and guides us into a deeper, more obedient, and truthful walk with our Lord.

#### Questions for Reflection
* **In what specific areas of your life or spiritual consumption do you most struggle with discerning God's voice from other influences or deceptive messages?**
* **How does a consistent, prayerful, and in-depth engagement with Scripture actively equip you to "know the word which the LORD hath not spoken" in your daily life?**
* **What concrete, practical steps can you commit to taking to cultivate a greater spirit of discernment in your daily life, particularly in your consumption of spiritual content and media?**
* **How does active participation in and accountability within the community of believers (the local church) contribute to our collective and individual ability to discern truth from error?**

### FAQ
**How does Deuteronomy 18:21 relate to the concept of modern-day prophecy and spiritual discernment?**

Answer: Deuteronomy 18:21, by posing the fundamental question of discernment, establishes an enduring principle that any claim to divine revelation must be verifiable and consistent with God's established truth. While the direct office of the Old Testament prophet as a primary source of new, authoritative revelation for all of God's people has ceased with the completion of the biblical canon, the New Testament acknowledges a continuing gift of prophecy within the church (e.g., [1 Corinthians 14](/1_corinthians/14 "1 Corinthians 14 - Prophecy and Tongues")). For modern-day claims of prophecy or spiritual messages, the same underlying principles of discernment apply with even greater urgency. Any prophetic utterance must align perfectly and without contradiction with the already revealed, inerrant Word of God (the Bible), serve to build up and encourage the church, and ultimately come to pass if it involves a predictive element. If it contradicts Scripture, fails to materialize, or does not bear good fruit, it is not from God. The profound question in [Deuteronomy 18:21](/deuteronomy/18-21 "Deuteronomy 18:21 - How Shall We Know?") compels us to ask, "Is this truly God's word?" and [Deuteronomy 18:22](/deuteronomy/18-22 "Deuteronomy 18:22 - The Test of a True Prophet") provides the timeless, infallible test for all such claims.

### CHRIST-CENTERED FULFILLMENT
Deuteronomy 18:21, with its urgent and existential question of how God's people could truly discern the authentic word of the LORD, finds its ultimate, perfect, and definitive fulfillment in the person and work of Jesus Christ. The foundational promise of a "prophet like Moses" in [Deuteronomy 18:15](/deuteronomy/18-15 "Deuteronomy 18:15 - The Promise of a Prophet like Moses") is explicitly and powerfully applied to Jesus in the New Testament (e.g., [Acts 3:22-23](/acts/3-22-23 "Acts 3:22-23 - Peter's Sermon on Jesus as the Prophet")). Jesus is not merely a prophet among many; He is the very **Word of God incarnate** ([John 1:1](/john/1-1 "John 1:1 - The Word Was God"), [John 1:14](/john/1-14 "John 1:14 - The Word Became Flesh")). His entire life, His authoritative teachings, His miraculous signs, and ultimately His sacrificial death and glorious resurrection, perfectly validated His divine origin and the absolute truth of every word He uttered. Unlike any human prophet, Jesus never spoke a word "which the LORD hath not spoken" because He was eternally one with the Father, speaking only what the Father commanded and revealing the Father's perfect will ([John 12:49-50](/john/12-49-50 "John 12:49-50 - Jesus Speaks the Father's Words")). Therefore, the profound question posed in [Deuteronomy 18:21](/deuteronomy/18-21 "Deuteronomy 18:21 - How Shall We Know?") is definitively and triumphantly answered in Christ: we know the true word of the LORD because it is embodied, perfectly expressed, and fully revealed in Jesus, the Son through whom God has truly and finally spoken to humanity ([Hebrews 1:1-2](/hebrews/1-1-2 "Hebrews 1:1-2 - God Has Spoken by His Son")). He is the ultimate, living standard against which all other claims to truth and divine revelation must be measured and found either true or false.

Note: Commentary is generated by AI with a directive for Biblical fidelity. Always rely on the Holy Spirit for discernment. The Scripture text and cross-references are from verified, non-AI sources.

Cross-References

1 John 4:1

¶ Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.

1 John 4:3

And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that [spirit] of antichrist, whereof ye have heard that it should come; and even now already is it in the world.

1 Thessalonians 5:24

Faithful [is] he that calleth you, who also will do [it].

Revelation 2:2

I know thy works, and thy labour, and thy patience, and how thou canst not bear them which are evil: and thou hast tried them which say they are apostles, and are not, and hast found them liars: