President Ezra Taft Benson taught: "The Lord works from the inside out. The world works from the outside in. The world would take people out of the slums. Christ takes the slums out of people and then they take themselves out of the slums. The world would mold men by changing their environment. Christ changes men who then change their environment. The world would shape human behavior, but Christ can change human nature." (Teachings of Ezra Taft Benson, pg. 79)
Similarly, Elder Boyd K. Packer taught: "True doctrine, understood, changes attitudes and behavior. The study of the doctrines of the gospel will improve behavior quicker than a study of behavior will improve behavior." (Little Children)
Then, what is true doctrine?
The Prophet 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.” (TPJS, sel. Joseph Fielding Smith , 121)
This truth is what Elder Boyd K. Packer has referred to as "the very root of Christian doctrine." "You may know much about the gospel as it branches out from there," Elder Packer continued, "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."
The Lord himself taught: "I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing." (John 15:5)
In a later revelation, the Lord taught his disciples:
"And again, I command thee that thou shalt pray vocally as well as in thy heart; yea, before the world as well as in secret, in public as well as in private.
And thou shalt declare glad tidings, yea, publish it upon the mountains, and upon every high place, and among every people that thou shalt be permitted to see.
And thou shalt do it with all humility, trusting in me, reviling not against revilers.
And of tenets thou shalt not talk, but thou shalt declare repentance and faith on the Savior, and remission of sins by baptism, and by fire, yea, even the Holy Ghost.
Behold, this is a great and the last commandment which I shall give unto you concerning this matter; for this shall suffice for thy daily walk, even unto the end of thy life." (D&C 19:28-32)
Hyrum Smith, the brother of the Prophet Joseph Smith understood and followed this admonition: “Preach the first principles of the Gospel—preach them over again: you will find that day after day new ideas and additional light concerning them will be revealed to you. You can enlarge upon them so as to comprehend them clearly. You will then be able to make them more plainly understood by those who teach.” (History of the Church, 6:323)
And what are the first principles of the Gospel?
"We believe that the first principles and ordinances of the Gospel are: first, Faith in the Lord Jesus Christ; second, Repentance; third, Baptism by immersion for the remission of sins; fourth, Laying on of hands for the gift of the Holy Ghost." (Articles of Faith 1:4)
For a deeper understanding of and appreciation for how the Lord works, for true doctrine, and for the good news of Jesus Christ and the first principles of the Gospel, I suggest Elder Maxwell's timeless classic Not My Will, but Thine.