Joseph Smith taught that “the fundamental principles of our religion are the testimony of the Apostles and Prophets, concerning Jesus Christ, that He died, was buried, and rose again the third day, and ascended into heaven; and all other things which pertain to our religion are only appendages to it” (Teachings, p. 121).
All doctrines and principles and practices have meaning-are of efficacy, virtue, or force-only to the degree that they are rooted in and anchored to the atonement of Jesus Christ.
In the words of Elder Boyd K. Packer: “Truth, glorious truth, proclaims there is ... Mediator. .... Through Him mercy can be fully extended to each of us without offending the eternal law of justice. This truth is the very root of Christian doctrine.
You may know much about the gospel as it branches out from there, but if you only know the branches and those branches do not touch that root, if they have been cut free from that truth, there will be no life nor substance nor redemption in them.” (CR, April 1977, p. 80.)