Doctrines, Principles, and Applications are the Why, What and How of the Gospel of Jesus Christ.
A gospel doctrine is a truth—a truth of salvation revealed by a loving Heavenly Father. Gospel doctrines are eternal, do not change, and pertain to the eternal progression and exaltation of Heavenly Father's sons and daughters... Gospel doctrines answer the question of "why?" (David Bednar, “Increase in Learning”, (2011) p. 151-152, 154, quoted at ScottWoodward.org)Principles
A gospel principle is a doctrinally based guideline for the righteous exercise of moral agency. Principles are subsets or components of broader gospel truths. Principles provide direction. Correct principles always are based upon and arise from doctrines, do not change, and answer the question of "what?" (David Bednar, “Increase in Learning”, (2011) p. 154-155, quoted at ScottWoodward.org)Applications
Applications are the actual behaviors, action steps, practices, or procedures by which gospel doctrines and principles are enacted in our lives. Whereas, doctrines and principles do not change, application appropriately can vary according to needs and circumstances. Applications answer the question of “how?” (David Bednar, “Increase in Learning” pg. 156, quoted at KeyStoneEducation)-
Somehow we seem to be drawn to applications as the primary way to "fix" things, to make life better, to be "doers of the word," to achieve desired outcomes, and to help the Church operate effectively. And far too often we emphasize applications without the necessary understanding and divorced from the doctrinal context. We may focus on applications because we like to believe and feel like we are in control, because we have confidence in our own experience and expertise-"the arm of flesh" (2 Nephi 4:34)-or because we are only doing what we have seen other teachers and leaders do. We may think as we serve in a quorum or auxiliary, "I am going to make this happen; I am going to manage this the right way." We all would do well to remember that The Church of Jesus Christ of Latter-day Saints is the Lord's Church, and He is able to do His own work (2 Nephi 27:20). (David Bednar, “Increase in Learning”, quoted at randommormon.blogspot.com)-
Whatever the reasons, emphasizing applications to the exclusion of fundamental doctrines and principles does not produce spiritual power, protection, and direction. (David Bednar, “Increase in Learning”, quoted at randommormon.blogspot.com)-
"the answers always are in the doctrines and principles of the gospel" (Increase in Learning, p. xv, quoted at, oneclimbs.com)
And now, as the preaching of the word had a great tendency to lead the people to do that which was just—yea, it had had more powerful effect upon the minds of the people than the sword, or anything else, which had happened unto them—therefore Alma thought it was expedient that they should try the virtue of the word of God. (Alma 31:5)