D&C 21

With the organization of Christ's Church in modern days, the Savior instructed the president of the Church -

"...there shall be a record kept among you; and in it thou shalt be called a seer, a translator, a prophet, an apostle of Jesus Christ, an elder of the church through the will of God the Father, and the grace of your Lord Jesus Christ..." (Doctrine and Covenants Section 21:1)

I think it is important to understand that the president serves by virtue of -

"...the will of God the Father, and the grace of your Lord Jesus Christ..." (Doctrine and Covenants Section 21:1)

The prophet is to be -

"...inspired of the Holy Ghost to lay the foundation thereof, and to build it up unto the most holy faith." (Doctrine and Covenants Section 21:2)

Because -

"Him have I inspired to move the cause of Zion in mighty power for good, and his diligence I know, and his prayers I have heard." (Doctrine and Covenants Section 21:7)

The members -

"...shalt give heed unto all his words and commandments which he shall give unto you as he receiveth them, walking in all holiness before me..." (Doctrine and Covenants Section 21:4)

Notice the commandment "shalt" - not should or may for the Savior said -

"For his word ye shall receive, as if from mine own mouth, in all patience and faith." (Doctrine and Covenants Section 21:5)

And provides this great promise -

"For by doing these things the gates of hell shall not prevail against you; yea, and the Lord God will disperse the powers of darkness from before you, and cause the heavens to shake for your good, and his name's glory." (Doctrine and Covenants Section 21:6)

"For, behold, I will bless all those who labor in my vineyard with a mighty blessing, and they shall believe on his words, which are given him through me by the Comforter, which manifesteth that Jesus was crucified by sinful men for the sins of the world, yea, for the remission of sins unto the contrite heart." (Doctrine and Covenants Section 21:9)