We fear our heavenly Father, in the context of these verses, because he judges our (believers) words and works impartially. But the context for that judgement is clear also. Knowing that He sent Jesus Christ who redeemed us away from perishable and worldly things which were part of our futile way of life unto a living hope in God, we are now responsible to live and act unto this new life. We are eternally secure but temporally responsible for the ministry of His blessings to us. A healthy fear of God can motivate us in the power of the Holy Spirit to minister beyond that which we ever thought we were capable.