In the Old Testament, under the Mosaic Law, the firstborn son inherited his father's property and blessing (see Deuteronomy 21:17). All firstborn sons were devoted to God as an acknowledgement that Israel as a nation owed their deliverance from Egypt to Him, and under the Law, the firstborn were redeemed by the offering of a lamb in sacrifice (see Exodus 13:2).

God did not always choose the firstborn for His purposes. Isaac and Jacob were not firstborn sons. Reuben, Jacob's eldest son was disinherited, and David, God's chosen king, was the youngest of the eight sons of Jesse.

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