In the Bible a fool is not an imbecile, or one who lacks intelligence, but one who foolishly chooses to ignore God and His ways; for example

"The fool says in his heart, 'There is no God.'" (Psalm 14:1).

Or he is one who doubts God's promises, or does not believe that God has spoken through his prophets in the Old Testament. Jesus said to two of his disciples:

"How foolish you are, and how slow of heart to believe all that the prophets have spoken!" (Luke 24:25).

Faith
  1. Trust
  2. Belief
Fall
Fast
Father
Fear
Fellowship
First Born
The "firstborn from the dead"
First fruits
Flesh
Fool
Forgive, Forgiveness
Foundation (Stone)
  1. The foundation of the earth
  2. The foundation of faith
Fulfil