Over and over again the consistent message from LDS apostles and prophets is that Mormon doctrine comes from the scriptures (the four standard works) as interpreted by prophets and apostles. The way new doctrine or modification of present doctrine comes is by revelation to the President of the Church (such as section 138 and the two Official Declarations in the Doctrine and Covenants). As fundamental as this principle is, many still seek to change, reinterpret, alter, or reject church doctrine. The reason is usually because some of it does not mesh with modern social issues and the philosophies of men.
Along with this and future blog posts in this series, readers are encouraged to review the following essays on the subject: the Mormon Newsroom article on Approaching Mormon Doctrine, Robert L. Millett’s fine longer examination What is Our Doctrine, and FairMormon’s piece on What is “Official” LDS Doctrine.
Other authors and bloggers have also posted various opinions on the subject but often (though not always) these are so academically oriented or misinformed (or even hostile) as to be either worthless or worse than worthless.
The below quotations should help with providing a more rounded perspective of how to determine genuine, authentic, gospel doctrine. Later blog posts will continue with this important matter as it relates to prophets, scripture, teaching, and revelation: