The sin that leads to eternal separation from God is unbelief.
Les Feldick teaches that no particular word or deed condemns a person; the only thing that condemns a human being is unbelief. Israel could not enter God's rest at Kadesh-Barnea because they refused to believe what God had promised. At the Great White Throne, people are lost because they did not believe the Gospel and rejected the pardon already provided through Christ's death and resurrection.
Hebrews 3:19 — This verse directly states that Israel could not enter into God's rest because of unbelief, showing what keeps people out of God's rest.
Hebrews 3:18 — God swore that those who believed not would not enter His rest, tying entrance into rest to believing God.
Hebrews 3:16-19 describes Israel's wilderness failure: "For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses. But with whom was he grieved forty years? was it not with them that had sinned, whose carcases fell in the wilderness? And to whom sware he that they should not enter into his rest, but to them that believed not? So we see that they could not enter in because of unbelief." The reason Israel did not enter God's rest is that they did not believe. Hebrews 11:6 adds, "But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him." Hebrews 9:22 also says, "And almost all things are by the law purged with blood; and without shedding of blood is no remission." Scripture connects entrance into God's rest with believing what God has said and approaching Him through faith and blood atonement.
Les Feldick teaches that the only sin that will condemn any human being is unbelief - refusing to believe what God has said about the work of the cross. God can forgive the vilest of sins, but when people refuse to believe that Christ died for them, paid their sin debt, and rose from the dead, their doom is sealed. He uses Israel at Kadesh-Barnea as a graphic illustration: Israel stood at the border of the Promised Land and could not enter because of unbelief, not because of the sins they committed around the golden calf. At the Great White Throne, Les says people will not be condemned because of their sins; they will be condemned because they did not believe the Gospel. Their sins were already atoned for, but unless a person appropriates God's grace by faith, the pardon is not applied. He warns that many 'awful good people' will stand there because they tried to work their way to heaven rather than simply believing that Christ's death has done it all. The rejection of the pardon is what makes eternal regret so intense. God has reconciled the world to Himself, not imputing their trespasses, but a pardon must be received by faith. Those who reject it will end up in the lake of fire because they rejected the pardon offered to them.
Israel's failure at Kadesh-Barnea was not that they committed immorality around the golden calf; that was vile sin, but God could forgive it. Their real problem was unbelief - they could not believe what God said. God had promised to send hornets ahead of them and drive out the Canaanites, but Israel said they were like grasshoppers and could not take the land. Because of their unbelief, they could not enter into God's rest. Les says nothing has changed: people are still kept out of God's rest by unbelief.
Les teaches that at the Great White Throne, the reason people stand as lost is because they did not believe the Gospel. It is not their sin that is condemning them; it is their unbelief. Even though their sins were atoned for, they did not appropriate the grace and love of God and believe it for salvation. They reject the pardon, and they will give an account of every word and deed done in a life of rebellion. Many people who were outwardly good will be there because they tried to work their way to heaven.
Les says God can forgive to the uttermost any sin, the vilest of sin, except one - unbelief. When people refuse to believe that Christ died for them, paid their sin debt, and rose from the dead, their doom is sealed. The only thing that will condemn anybody, Jew or Gentile, rich or poor, is not a word spoken or a deed done; it is unbelief.
Israel's Unbelief at Kadesh-Barnea
Les identifies Israel's refusal to believe God's promise about the land as unbelief, the reason they could not enter God's rest.
Unbelief at the Great White Throne
Les teaches that at the Great White Throne, sin is not what condemns the lost; their unbelief is.
Rejecting the Pardon
Les explains that people end up in the lake of fire because they rejected the pardon God has already provided, not because of their sins.
Unbelief Is the Only Unforgivable Sin
Les says God can forgive any sin except unbelief, because refusing to believe the Gospel seals a person's doom.
Golden Calf Was Not the Condemning Issue
Les points out that God did not hold the golden calf immorality against Israel; their problem was unbelief.
Only Unbelief Condemns
Les declares that the only thing that will condemn a human being is unbelief, not particular words or deeds.
Good People Who Did Not Believe
Les warns that many outwardly good people will stand at the Great White Throne because they did not believe the Gospel and did not appropriate God's grace.
Without Faith No One Can Please God
Les connects Israel's lack of faith to the truth that without faith and the shedding of blood there is no approach to God.
Hebrews 3:19: So we see that they could not enter in because of unbelief.
This is the key verse that directly says unbelief kept Israel out of God's rest.
Hebrews 3:18: And to whom sware he that they should not enter into his rest, but to them that believed not?
God's oath shows that refusal to believe, not any specific sin, was the bar to entering His rest.
Hebrews 11:6: But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.
Faith is the essential requirement for pleasing God, which Les connects to Israel's failure.
Hebrews 9:22: And almost all things are by the law purged with blood; and without shedding of blood is no remission.
Les references this truth that approach to God requires blood atonement and faith.
Yes. Les Feldick teaches that no particular word or deed condemns anyone; the only thing that will condemn a human being is unbelief. God can forgive the vilest sins, but refusing to believe that Christ died, paid the sin debt, and rose again leaves a person without the pardon.
Les explains that many 'awful good people' will stand at the Great White Throne because they had no intention of missing heaven, but they tried to work their way in. Entrance to heaven is not by works; it is by believing that Christ's death has done it all.
Israel stood at the Promised Land but said they could not take it because the people were like giants. God could forgive their sins, such as the golden calf worship, but their unbelief kept them from entering God's rest. Les says nothing has changed: unbelief is still the one thing that keeps people from God's provision.
Watch the Teaching: The Truth About Grace, Faith & Abraham — Romans 4:13-25