Pastor Robb Gossen's sermon "Fight For Eternity" challenges believers to actively engage in the fight of faith, drawing inspiration from a boxer's Olympic journey. The main focus is on 1 Timothy 6:12, urging Christians to pursue eternal life with vigor and determination. The sermon stresses that the battle is spiritual and requires discipline and endurance, likening it to training for the Olympics of life. Believers are called to confidently embrace their unique roles in God's kingdom, persisting in the fight with the assurance that God is with them in the victory.