And He did not do many mighty works there because of their unbelief.
Immediately the father of the child cried out with tears, “Lord, I believe. Help my unbelief!”
Afterward He appeared to the eleven as they sat at supper, and He reprimanded them for their unbelief and hardness of heart, because they did not believe those who had seen Him after He had risen.
Then He said to Thomas, “Put your finger here, and look at My hands. Put your hand here and place it in My side. Do not be faithless, but believing.”
Against all hope, he believed in hope, that he might become the father of many nations according to what was spoken, “So shall your descendants be.”
And not being weak in faith, he did not consider his own body to be dead (when he was about a hundred years old), nor yet the deadness of Sarah’s womb.
He did not waver at the promise of God through unbelief, but was strong in faith, giving glory to God,
and being fully persuaded that what God had promised, He was able to perform.
Therefore “it was credited to him as righteousness.”
So we see that they could not enter because of unbelief.