'Doubt' in the Bible

And immediately Jesus stretched forth his hand, and took hold of him, and saith unto him, O thou of little faith, wherefore didst thou doubt?

And Jesus answered and said unto them, Verily I say unto you, If ye have faith, and doubt not, ye shall not only do what is done to the fig tree, but even if ye shall say unto this mountain, Be thou taken up and cast into the sea, it shall be done.

Verily I say unto you, Whosoever shall say unto this mountain, Be thou taken up and cast into the sea; and shall not doubt in his heart, but shall believe that what he saith cometh to pass; he shall have it.

And when the barbarians saw the venomous creature hanging from his hand, they said one to another, No doubt this man is a murderer, whom, though he hath escaped from the sea, yet Justice hath not suffered to live.

And on some have mercy, who are in doubt;