Hebrews 11:1 says that "faith is being sure of what we hope for and certain of what we do not see." Without a doubt, every Witness would probably insist that their faith agrees with this definition. They're sure and certain of what they have been told.
One example of faith is Noah, who is mentioned in the January 15, 1998 issue of The Watchtower. In the article, "Walking By Faith Not By Sight," the reader is told that Noah's faith was well founded. This is supported by the fact that Noah was certain God would do what he said he was going to do. Noah was even told when the flood would occur. In Genesis 7:4, God said to Noah, "Seven days from now I will send rain on the earth for forty days and forty nights...". (The article says that God did not give Noah a date when the Deluge would begin, but this is obviously incorrect according to the above scripture.) In the end, God did exactly what he had told Noah he was going to do. The things Noah was certain and sure of did occur.
While Noah's faith proved well founded, how would a Witness prove his or her faith is well founded? Well, if God speaks through the Society, like he spoke through Noah, then the Society's predictions must come true. Sadly, every single prophecy pronounced by the Society has failed. Two of those prophecies, which are related to faithful men of the bible, are below:
o "1925 will mark the return of Abraham, Isaac, Jacob, and the faithful prophets of old." (Millions Now Living Will Never Die, pp. 88-90)
o "Our thought is, that 1925 is definitely settled by the Scriptures. As to Noah, the Christian now has much more upon which to base his faith than Noah had upon which to base his faith in the coming deluge." (The Watchtower, April 1, 1923, p.106)
Apparently, the Witnesses' faith is anything but sure and it obviously is not certain.