God judged the Israelites in the wilderness because of their unbelief.
At Kadesh Barnea, Israel stood at the border of the land God had promised and refused to believe that He would drive out their enemies. Their fearful request for spies was already a step of unbelief, and when the spies returned with a discouraging report, the people concluded they could not take the land. Hebrews 3:19 says plainly that they could not enter in because of unbelief.
Hebrews 3:19 — This verse gives the direct biblical answer: the wilderness generation could not enter God's rest because of unbelief.
Psalm 95:10-11 — God Himself describes the forty-year wilderness judgment and His oath that that generation would not enter His rest.
The Bible identifies the wilderness generation as those who came out of Egypt under Moses but provoked God (Hebrews 3:16). God was grieved with them for forty years—with those who sinned, whose carcasses fell in the wilderness (Hebrews 3:17). The oath that they should not enter His rest was sworn to those who believed not (Hebrews 3:18). The conclusion is explicit: "So we see that they could not enter in because of unbelief" (Hebrews 3:19). Psalm 95:10-11 describes the same generation as a people who erred in their heart and did not know God's ways, and it records God swearing in His wrath that they should not enter into His rest. The consistent biblical testimony is that unbelief was the cause of their judgment.
Les places the judgment squarely on Israel's unbelief at Kadesh Barnea. He emphasizes that God had already promised to drive out the Canaanites, using hornets or whatever was needed, so that Israel could simply walk in and take the land. Instead, Israel's first step of unbelief was to demand spies; God never instructed those twelve spies but condescended to their request. After the spies returned with a fearful report, the people said they could not take the land—they were like grasshoppers before walled cities. Les contrasts this with the earlier golden calf incident. Gross immorality had occurred only months before, yet at Kadesh God did not bring up their immorality; He confronted their unbelief. According to Les, this is why the writer of Hebrews emphasizes unbelief as the cause of that generation's judgment.
Les reminds listeners that only a few months before Kadesh Barnea, while Moses was on the mountain, Israel had fallen into the golden calf incident. Aaron made the calf from their gold, and the people were involved in nakedness, seductive dancing, and gross immorality. Yet when Israel later stood at Kadesh Barnea and refused to believe God's promise, God did not remind them of that immorality—He reminded them of their unbelief. That contrast, Les says, shows that the wilderness judgment was about unbelief.
According to Les, the people's demand to send spies was their first step of unbelief. It was not God's idea to send the twelve spies; God never instructed them to do that. He finally condescended and allowed it. The spies were gone for forty days, and when they returned, the report led Israel to reject the land. So the process itself began from a heart of unbelief.
Les points to Hebrews 3, which he says is rehearsing the event at Kadesh Barnea. The chapter asks who provoked God and with whom He was grieved forty years—the answer is those who sinned and whose carcasses fell in the wilderness. Les emphasizes that Hebrews is not pointing to the golden calf immorality but to unbelief as the root issue. Only a remnant, Joshua, Caleb, and a few others, were spared.
Les warns believers to learn from that "horrible experience" and to watch for "the evil heart of unbelief." He says God hates nothing more than when He says something and we do not believe it. The wilderness judgment is therefore a standing warning that unbelief, not just outward immorality, is what provokes God.
The First Step of Unbelief at Kadesh
Les shows that Israel's demand to send spies into the Promised Land was itself a step of unbelief, because God had already promised to drive out the Canaanites.
The Generation That Fell in the Wilderness
Les identifies the generation that came out of Egypt with Moses as being, for the most part, totally in unbelief, so that only a few escaped the wilderness judgment.
Hebrews Rehearses Kadesh Barnea
Les treats Hebrews 3:15-17 as rehearsing Israel's provocation at Kadesh Barnea, including the question of who grieved God for forty years.
The Oath That They Should Not Enter
Les reads Hebrews 3:15-18 as showing that God was grieved with the wilderness generation and swore they should not enter His rest.
Unbelief, Not Sin, Is the Condemning Issue
Les states plainly that for Israel, it is not their sin that condemns but their unbelief—they rejected God's promise and said they could not take the land.
The Psalmist's Forty Years
Les connects Psalm 95's description of the forty years of testing and God's oath with the writer of Hebrews clarifying the issue as unbelief.
The Golden Calf vs. Kadesh Barnea
Les contrasts the golden calf immorality of a few months earlier with what God confronted at Kadesh—there God did not bring up their immorality but their unbelief.
The Evil Heart of Unbelief
Les draws a warning from Israel's experience: the "evil heart of unbelief" is what provokes God, and believers should learn from that horrible experience.
Hebrews 3:16: For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses.
Shows that not everyone from Egypt provoked God, but the wilderness generation did.
Hebrews 3:17: But with whom was he grieved forty years? was it not with them that had sinned, whose carcases fell in the wilderness?
Identifies those under judgment as the sinners whose bodies fell in the wilderness.
Hebrews 3:18: And to whom sware he that they should not enter into his rest, but to them that believed not?
States that the excluded group is those who did not believe.
Hebrews 3:19: So we see that they could not enter in because of unbelief.
Explicitly names unbelief as the cause of their exclusion.
Psalm 95:10: Forty years long was I grieved with this generation, and said, It is a people that do err in their heart, and they have not known my ways:
God's own description of His forty-year grief with that generation.
Psalm 95:11: Unto whom I sware in my wrath that they should not enter into my rest.
The oath that sealed their exclusion from rest.
The main reason was unbelief. At Kadesh Barnea, God promised to drive out their enemies and give them the land, but Israel would not take Him at His word. Hebrews 3:19 says they could not enter in because of unbelief.
Les notes that Israel sinned grossly around the golden calf only months before, and God did judge that act. But when they later refused to enter the land, God did not remind them of their immorality—He confronted their unbelief. The wilderness judgment was about their refusal to believe God's promise.
Les says that for the most part the generation old enough to respond was totally in unbelief. Only Joshua, Caleb, and a few others remained as a remnant of that generation.
Watch the Teaching: The Truth About Grace, Faith & Abraham — Romans 4:13-25