Gospel Principles defines New and Everlasting Covenant.
Gospel Principles (Salt Lake City, UT: The Church of Jesus Christ of Latter-day Saints, 2009), 85
The New and Everlasting Covenant
What do we promise to do when we accept the gospel? What blessings does Heavenly Father give us as we keep these promises?
The fulness of the gospel is called the new and everlasting covenant. It includes the covenants made at baptism, during the sacrament, in the temple, and at any other time. The Lord calls it everlasting because it is ordained by an everlasting God and because the covenant will never be changed. He gave this same covenant to Adam, Enoch, Noah, Abraham, and other prophets. In this sense it is not new. But the Lord calls it new because each time the gospel is restored after being taken from the earth, it is new to the people who receive it (see Jeremiah 31:31–34; Ezekiel 37:26).
When we accept the new and everlasting covenant, we agree to repent, be baptized, receive the Holy Ghost, receive our endowments, receive the covenant of marriage in the temple, and follow and obey Christ to the end of our lives. As we keep our covenants, our Heavenly Father promises us that we will receive exaltation in the celestial kingdom (see D&C 132:20–24; see also chapter 47 in this book).
The greatness of that promise is hard for mortals to understand. The commandments He gives are for our benefit, and as we are faithful we may forever share the blessings and beauties of heaven and earth. We may live in His presence and partake of His love, compassion, power, greatness, knowledge, wisdom, glory, and dominions.
What does being the Lord’s covenant people have to do with how we dress, act, and keep the commandments of God?