And he did not do many mighty works there, because of their unbelief.

And he marveled because of their unbelief. And he went about among the villages teaching.

Immediately the father of the child cried out and said, “I believe; help my unbelief!”

The Great Commission

Afterward he appeared to the eleven themselves as they were reclining at table, and he rebuked them for their unbelief and hardness of heart, because they had not believed those who saw him after he had risen.

While you have the light, believe in the light, that you may become sons of light.”

The Unbelief of the People

When Jesus had said these things, he departed and hid himself from them.

But when some became stubborn and continued in unbelief, speaking evil of the Way before the congregation, he withdrew from them and took the disciples with him, reasoning daily in the hall of Tyrannus.

No unbelief made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God,

Israel's Unbelief

What shall we say, then? That Gentiles who did not pursue righteousness have attained it, that is, a righteousness that is by faith;

That is true. They were broken off because of their unbelief, but you stand fast through faith. So do not become proud, but fear.

And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again.

though formerly I was a blasphemer, persecutor, and insolent opponent. But I received mercy because I had acted ignorantly in unbelief,

So we see that they were unable to enter because of unbelief.