Even though I walk through the valley of the shadow of death, I will fear no evil, for you are with me; your rod and your staff, they comfort me.
Will I never fear evil? Will I be stoic and unmoved when I see evil rise against me, or my own sinful desires well up within me? I think not. Rather, think in this light.
As the sheep is lead by the shepherd, there is still fear on the part of the sheep when a wolf is spotted, or when it gets wanders and gets stuck. However, there is a different level of fear on the part of a sheep who does not have a shepherd with a rod to defend against the wolf, or a staff to rescue.
The terror that overcomes a sheep who must fend for itself is unknown to us as the sheep of the Good Shepherd. We are not frightened as one who must rely on self to be his own strong tower or deliverer, having not the strength to wield a rod or staff. Even as you say, “You are with me,” hear the Savior say, “I am with you.” (Matt 28:20)