Can I undoubtedly remove a mountian with faith by words along, according to Jesus?

"Jesus answered and said unto them: 'Verily I say unto you, if ye have faith and doubt not, ye shall not only do this, which is done to the fig tree, but also, if ye shall say unto this mountain: 'be thou removed, and be thou cast into the sea;' it shall be done.'" -- Matthew 21:21 (King James Version)