Deuteronomy 18: 21-22 - How Shall We Know the Word the LORD Hath Not Spoken | Speak His Word Only

Deuteronomy 18:21–22 KJV

“And if thou say in thine heart, How shall we know the word which the LORD hath not spoken? When a prophet speaketh in the name of the LORD, if the thing follow not, nor come to pass, that is the thing which the LORD hath not spoken, but the prophet hath spoken it presumptuously: thou shalt not be afraid of him.”

Deuteronomy 18:21–22 establishes an important biblical principle concerning prophecy, discernment, and accountability. God did not command Israel to accept every person who claimed to speak in His name. He gave His people standards by which prophetic claims were to be tested.

“How Shall We Know?”

This is an important question.

If someone stood before Israel and declared, “The LORD said,” how could the people know whether God had actually spoken?

God did not require blind acceptance.

He provided a test.

This teaches us an important principle: a claim of divine revelation does not authenticate itself merely because someone attaches God's name to it.

The words must be tested.

“When a Prophet Speaketh in the Name of the LORD”

The seriousness of this passage comes from the prophet claiming to represent God.

The person was not merely giving an opinion.

He was effectively declaring:

“This message came from the LORD.”

That places tremendous responsibility upon anyone claiming divine revelation.

There is a great difference between saying:

“I believe...”

and saying:

“The LORD said...”

The second statement claims divine authority.

Therefore, Scripture treats speaking presumptuously in God's name as a serious matter.

“If the Thing Follow Not, Nor Come to Pass”

When a prophet gave a definite prediction in the name of the LORD, fulfillment provided an objective test.

If the prophet declared that God said something would happen and the predicted event did not occur, God said:

“that is the thing which the LORD hath not spoken.”

The failure was not to be explained away merely because the individual appeared spiritual, sincere, charismatic, or influential.

The prophecy had failed its test.

This demonstrates an important biblical principle:

God is responsible for fulfilling what God actually speaks.

Isaiah 46:10 describes Him as:

“Declaring the end from the beginning, and from ancient times the things that are not yet done...”

God does not need human beings to manipulate circumstances to make His word appear true.

“The Prophet Hath Spoken It Presumptuously”

The word presumptuously is crucial.

The idea is that the prophet has spoken with unauthorized boldness—speaking something as God's word when God had not actually given that word.

This warns against allowing personal thoughts, emotions, desires, assumptions, or impressions to be automatically elevated to the level of divine revelation.

Someone may sincerely believe something and still be mistaken.

Sincerity alone does not transform human thoughts into God's word.

Therefore, anyone claiming to speak prophetically should maintain reverence concerning the words:

“Thus saith the LORD.”

Fulfillment Alone Is Not the Only Test

Deuteronomy 18 must be read together with Deuteronomy 13:1–3.

There God describes a prophet or dreamer who gives a sign that actually comes to pass, yet afterward says:

“Let us go after other gods...”

Israel was commanded not to follow that prophet.

This gives us two important principles.

A prediction that fails demonstrates that the particular prediction was not spoken by the LORD.

But a prediction that comes to pass does not, by itself, prove that the speaker is from God.

The message must also agree with God's revealed truth.

Therefore biblical discernment asks both:

Did the prophetic word prove true?

and

Does the message agree with what God has already revealed?

God does not contradict Himself.

“Thou Shalt Not Be Afraid of Him”

This final statement is powerful.

False claims of divine authority can create fear.

A person may think:

“What if this prophet has power over my future?”

“What if something happens because I questioned the prophecy?”

“What if I am disobeying God by testing what was spoken?”

But God told Israel:

“thou shalt not be afraid of him.”

The authority belonged to God—not to the person claiming to speak for Him.

If God had not spoken the message, Israel was not required to fear the speaker.

Prophecy Must Be Judged

The New Testament continues the principle that prophetic speech is subject to discernment.

1 Corinthians 14:29 KJV says:

“Let the prophets speak two or three, and let the other judge.”

And 1 Thessalonians 5:20–21 KJV says:

“Despise not prophesyings. Prove all things; hold fast that which is good.”

Notice the balance.

Scripture does not say:

Despise prophecy.

Neither does it say:

Believe every prophecy.

It says:

Prove all things.

This protects both the operation of spiritual gifts and the people receiving ministry.

A Warning for Those Who Prophesy

Deuteronomy 18 should produce humility in anyone who believes God has called them to prophetic ministry.

Not every thought is prophecy.

Not every dream is a message for someone else.

Not every strong impression should be announced as “God said.”

There must be reverence for God's name and His word.

When we are uncertain, it is wiser to acknowledge our uncertainty than to attach God's authority to something He has not spoken.

The prophetic gift does not remove accountability.

It increases accountability.

Personal Application

Deuteronomy 18:21–22 teaches us not to surrender our discernment simply because someone claims to have heard from God.

We should listen carefully.

We should pray.

We should examine Scripture.

We should judge what has been spoken.

And where a definite predictive word has been given, we should remember what God Himself established:

Did it come to pass?

At the same time, fulfillment alone is not sufficient. The message must never lead us away from the God revealed in Scripture or contradict His truth.

Our ultimate confidence must never rest in a prophet, preacher, teacher, dream, vision, or spiritual experience.

Our confidence rests in God.

A true prophetic ministry points people toward obedience to God rather than creating dependence upon the prophet.

And when someone speaks presumptuously in God's name, Scripture tells God's people plainly:

“Thou shalt not be afraid of him.”