'Doubt' in the Bible

But so that you may know that the Son of Man has the authority and power on earth to forgive sins”—He said to the paralyzed man,

For verily I say unto you, That whosoever shall say unto this mountain, Be thou removed, and be thou cast into the sea; and shall not doubt in his heart, but shall believe that those things which he saith shall come to pass; he shall have whatsoever he saith.