'Believes' in the Bible

Jesus said to him, "If you can believe, all things are possible to him who believes."

For most certainly I tell you, whoever may tell this mountain, 'Be taken up and cast into the sea,' and doesn't doubt in his heart, but believes that what he says is happening; he shall have whatever he says.

He who believes and is baptized will be saved; but he who disbelieves will be condemned.