Hebrews 4:1-3 (ESV)
Therefore, while the promise of entering his rest still stands, let us fear lest any of you should seem to have failed to reach it.  For good news came to us just as to them, but the message they heard did not benefit them, because they were not united by faith with those who listened.. For we who have believed enter that rest, as he has said,
“As I swore in my wrath,
‘They shall not enter my rest,’ ”
although his works were finished from the foundation of the world.
The Israelites were given a promise that they would enter the Promised Land. The reason that none of those (except Joshua and Caleb) who left Egypt actually entered the Promised Land was due to their unbelief. They did not believe that they could take the land. They did not believe God when He told them they could.
This may be a reference to the people’s response to the report of the spies who were sent in to spy out the land. The purpose of the spying was not to see if the land could be taken. It was to see the land that they were going to take. It was to formulate a plan for doing what God had said they would. “Look what God has given us!!” was to be the attitude, not “Look at how impossible it will be to take the land.”
The attitude that prevailed among the people once the spies reported was rank unbelief and God granted them their wish. They became a self fulfilling prophecy. “Since you do not think that the land can be taken, then you will not take it,” is what God virtually says to them. Faith in the promise was what prevented them from entering the land.
This episode in the life of Israel is preserved as an example and warning to us. If you do not believe the promise of God then you too will not enter God’s rest.
Many would say that the reason the Israelites did not enter the land was because of disobedience. And this would be true. But disobedience is a matter of unbelief and real faith will produce obedience. If they had believed they would have obeyed. This is crucial to always keep before us.
Faith without works is dead. It is not real faith. It is easy to say you believe. But if that belief does not produce fruit then the claim is false. The consequences are not small. The disobedience of the Israelites meant that they never entered the land that they had so looked forward to when they left Egypt. And unbelieving disobedience means for us that we shall never enter the rest that God has prepared for all those whose faith is in Christ.
The Israelites are an example for us. Learn from them. Do not think that because they were in the Old Covenant and we are in the New that we can sin and get away with it. The writer is clear. Their faithlessness led to disobedience which meant they were disqualified for the promise. The same is true for us. If we do not believe and obey we will never enter the rest that God prepares for His own.
This is not to be trifled with. Take your faith and the obedience it produces, very seriously. Do not think that God will simply overlook your unbelief and disobedience. He will not. God is not mocked. And unbelief and disobedience is a mocking of God. Turn from it. Come and really believe. Come and really obey out of a heart of faith. Your life and eternal rest depend upon it.