The sheepfolds in biblical times were constructed without a gate or door. The small opening from which the sheep would enter was the place where the shepherd would rest. This was the best way the shepherd could protect his sheep, as any predator or thief would have to get past him first.
In John chapter 10, the Savior references this and tells his disciples, “Verily, verily, I say unto you, I am the door of the sheep.” (John 10:7) I love the image of Christ being a shepherd, and also the gate or door. For He is the only way, or means, by which salvation can come. If we wish to be in His fold, He is the only way in.
The prophet Jacob also speaks of Christ as a gate: “O then, my beloved brethren, come unto the Lord, the Holy One. Remember that his paths are righteous. Behold, the way for man is narrow, but it lieth in a straight course before him, and the keeper of the gate is the Holy One of Israel; and he employeth no servant there; and there is none other way save it be by the gate; …” (2 Nephi 9:41)
And what a beautiful reminder that once we are in His fold, we are promised His protection. As David mentions in the 23rd Psalm: “The Lord is my shepherd; I shall not want. …Yea, though I walk through the valley of the shadow of death, I will fear no evil: for thou art with me; thy rod and thy staff they comfort me.” (Psalm 23:1, 4) He has our backs, and He will do anything, and indeed has done all, to save us. “I am the good shepherd: the good shepherd giveth his life for the sheep.” (John 10:11)