There is more than one answer as to what faith is. It means different things to different people. Some take it to mean any belief that is not based upon evidence. If that is your definition, then it is hard to see why it is valuable to God to put us here among untrustworthy people who attempt to mislead us for personal gain often and rests our salvation on a trait that would make us susceptible to them.
Another definition for faith is confidence, as in “I have faith in you. I have faith in myself. I have faith in God.” If you replace the all the instances of the word “faith” with the word “confidence,” a synonym, the scriptures render us a different meaning.
On the other hand, there is spiritual knowledge, which is quite different from knowledge derived with one’s mind. Paul writes that these things must be spiritually discerned, which is to say through communion with the Holy Spirit, spirit to spirit. The product of such is revelation, or spiritual knowledge, not just belief. When spiritual knowledge is combined with confidence, one can move mountains, and one is not susceptible to being misled by devils or human beings.
