For by grace are ye saved through faith; and that not of yourselves: it is the gift of God
Ephesians 2:8 KJV
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 KJV
So then faith comes by hearing, and hearing by the word of God.
Romans 10:17 KJV