apistia

(Translation from NRSV)

Matthew

13: 58

And he did not do many deeds of power there, because of their unbelief (apistia).

Mark

6: 6	And he was amazed at their unbelief (apistia). Then he went about among the villages teaching.
9: 24	Immediately the father of the child cried out, "I believe; help my unbelief (apistia)!"
16: 14	Later he appeared to the eleven themselves as they were sitting at the table; and he upbraided them for their unbelief (apistia) and stubbornness, because they had not believed those who saw him after he had risen.