Faith is an active reliance on God rather than the passive byproduct of intellectual assent.
Proclaiming a horse safe to ride is intellectual assent. Climbing into the saddle is faith. Believing God exists is intellectual assent. Faith is trusting him, despite our afflictions.
We frequently exercise faith in everyday life.
Most of us sit on chairs without first checking to see if they are structurally sound because we trust the expertise of the furniture builders. That is faith.
We believe airplane designers understand aerodynamics so we fly in their airplanes. That is faith.
We see evidence that chemists know how to make safe and effective medicines so we use their products. That is faith.
Amid affliction we may not understand why God lets us suffer, but we see evidence of his existence and excellence.
Based on these observations—not our feelings—we therefore trust that his love will not fail us and his ideas and methods will indeed turn out to be superior to ours.
That is faith.