To simply state the truth plainly and without apology to let others believe it as they see fit does not require any special calling. It is a privilege of members and nonmembers alike. Joseph Smith said: "Have the Presbyterians any truth? Yes. Have the Baptists, Methodists, etc., any truth? Yes. They all have a little truth mixed with error. We should gather all the good and true principles in the world and treasure them up, or we shall not come out true 'Mormons.'"
If a Presbyterian can state a truth and God would require us to believe that truth simply because it is true, then can we not see that it is the right of any man or woman member or non member alike to simply state and teach truth as they perceive it by the Holy Ghost.
Any man can teach the truth as he sees it and let his listeners judge for themselves and this requires no calling, nor even a membership in the true church.
But what is different altogether is for a man to offer a statement of revelation from Heaven as instruction. It is against the economy of heaven for a man to receive instruction from heaven for those above him. It is one thing to simply state the truth as purely as one can, and that is the privilege of nonmembers and members alike. It is another altogether to put forth something as a revelation from heaven.
Frequently we confuse the two. And for those that do, I again refer to Joseph Smith's statement. If we are bound by truths found among Baptists and Methodists, then we are bound by truth itself. And thus every man has a right to speak truth as purely as he can.
We should speak and learn by the Holy Ghost, rather than fretting over whether we are saying something that somebody already said.
But what a regular man or woman cannot do, and what is reserved in the keys of presidency, is to utter the words "I have had a revelation that ...." to those over whom he has no authority, instead of simply stating truth to the best of his ability, and letting others decide for themselves what portion of his words are uttered under the inspiration of the Holy Ghost, and what portion is no more than another man's meaningless opinion.
And how can one tell what is taught by the Holy Ghost and what is just another meaningless opinion of man? The answer is that as we teach by the Holy Ghost those who are prepared will learn by the Holy Ghost. Frequently they learn more than the teacher himself intended as he spoke, or even more than the teacher himself knew. The Holy Ghost manifests truth and they are edified and rejoice together.