The biblical definition of faith is found in Hebrews 11:1:
Now faith is the assurance of things hoped for, the conviction of things not seen.
From this definition, we learn several characteristics of faith. First, one who has faith possesses assurance , or confidence. This is different than hope, because faith is the “assurance of things hoped for.” Hope always leaves room for doubt. Hope always says “maybe.” For example, I might say, “I sure hope it rains today so that my garden will be watered.” I desire rain, but I’m not sure if it will rain. Faith, on the other hand, is always certain, the “assurance of things hoped for.”
What people call faith , or belief , is often not faith by biblical definition. They might look at dark clouds in the sky, for example, and say, “I believe it’s going to rain.” They aren’t, however, certain that it’s going to rain–they just think that there is a good possibility that it might rain. That is not biblical faith. Biblical faith has no element of doubt. It leaves no room for any outcome other than what God has promised.