http://scriptures.info/scriptures/nt/matthew/14.3#3Then the eleven disciples went away into Galilee, into a mountain where Jesus had appointed them. And when they saw him, they worshipped him, but some doubted. And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost, teaching them to observe all things whatsoever I have commanded you. And lo, I am with you always, unto the end of the world. Amen.
And wouldn't "teaching them to observe all things whatsoever I have commanded you" include this?
http://scriptures.info/scriptures/nt/matthew/9.10#10Moreover, if thy brother shall trespass against thee, go and tell him his fault between thee and him alone. If he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it unto the church; but if he neglect to hear the church, let him be unto thee as a heathen man and a publican. Verily, I say unto you, Whatsoever ye shall bind on earth, shall be bound in heaven; and whatsoever ye shall loose on earth, shall be loosed in heaven. Again, I say unto you, that if two of you shall agree on earth as touching anything that they shall ask, that they may not ask amiss, it shall be done for them of my Father which is in heaven. For where two or three are gathered together in my name, there am I in the midst of them.
So wouldn't the idea of teaching newcomers about a church (a corporate body with the powers of binding and loosing), and the idea of church discipline, and the power of the church to excommunicate any rebellious and unrepentant sinners all be implicitly included in "The Rock of Christ"?
If the restored scriptures really are scripture, and if you've covenanted to accept them as a guide for your lives and your teachings (and if Jesus really said the words recorded in what you now call Matthew 9:10), wouldn't all of that have to be included in His law?
And wouldn't comemorating His sacrifice in a communion service, with the elements of bread and wine representing His body and blood, also be included in what He commanded His disciples to teach those they made disciples of here?
Even though it's not explicitly mentioned in the 5th chapter of 3 Nephi?
And wouldn't that therefore also be part of His law, His doctrine?
And weren't the Apostles commanded to teach those they made disciples of here?
Would being taught of them (or anyone who truly holds the same priesthood and authority today--such as Denver, if he truly is a prophet) really be trusting in men (or in the arm of the flesh)?