And they, when they had heard that he was alive,
and had been seen of her, believed not.
Mark 16:11
Adam Clarke
Charles Spurgeon
Matthew Henry
Unbelief is very hard to kill, even in hearts that are right with God; so we need not wonder that divine grace is required to expel unbelief from the hearts of the unregenerate.
They could not give credit to the report she brought them. They heard that he was alive, and had been seen of her. The story was plausible enough, and yet they believed not. They would not say that she made the story herself, or designed to deceive them but they fear that she is imposed upon, and that it was but a fancy that she saw him. Had they believed the frequent predictions of it from his own mouth, they would not have been now so incredulous of the report of it.