Lesson #5 The Covenant Relationship is a mystery.
Colossians 1:26-27 tells us that the mystery is now made manifest to the saints which is Christ in you, the hope of glory. Once we understand that the phrase "Christ in you" is a reference to one of the steps of the ancient Hebrew covenant (covered in Lesson #10) then we know that the mystery is referring to the covenant relationship.
The combination of two Book of Mormon verses also tells us that the covenant relationship is a mystery. Alma 9:18 tell us that if we will not harden our hearts we will know the mysteries of God. The next verse, 3N 9:92, defines what it means to not harden our hearts"repent and come unto Me and be baptized in My name." We will learn in Lesson #11 that to "come unto Me and be baptized" represents the first two steps of the three step covenant relationship. Therefore, to not harden means to have a covenant and to have the mystery of the covenant revealed.
The layout of the tabernacle built by Moses according to specifications given by God also gives us the message that the covenant is a mystery. The tabernacle has three parts: the outer court, the holy place and the holy of holies. The last two are hidden inside the tent. The holy place has three pieces in furniture which are symbolic of the three steps of the covenant. The fact that they are hidden inside the tent tells us that the covenant is a mystery which is revealed only to those who exercise faith and repentance.
The mystery of the covenant relationship has been hidden from us because of the decisions of a few of our spiritual ancestors. The Lord is now opening this mystery up to us just in time to use it just as He is preparing to take the Book of Mormon to the Lamanites to restore what they lost as a result of the decisions of a few of their ancestors. Ask the Lord for your own revelation of the covenant relationship.