D&C 95

To the priesthood in Kirtland, the Lord said -

"...there are many who have been ordained among you, whom I have called but few of them are chosen.
6 They who are not chosen have sinned a very grievous sin, in that they are walking in darkness at noon-day." (Doctrine and Covenants Section 95:5 - 6)

We learned in Section 93 -

"The glory of God is intelligence, or, in other words, light and truth." (Doctrine and Covenants Section 93:36)

Wisdom and intelligence is choosing God and thus receiving light and truth. When we choose other than God, we "are walking in darkness at noon-day". The Lord asked -

"...there are many called, but few are chosen. And why are they not chosen?" (Doctrine and Covenants Section 121:34)

He answers -

"Because their hearts are set so much upon the things of this world, and aspire to the honors of men..." (Doctrine and Covenants Section 121:35)

As the Lord commanded -

"...the strength of my house, my young men and the middle aged—Gather yourselves together unto the land of Zion..." (Doctrine and Covenants Section 103:22)

...to rescue the saints in Missouri, He also commented -

"...this is my will; ask and ye shall receive; but men do not always do my will." (Doctrine and Covenants Section 103:31)

Thus their hearts are set upon the things of this world, walking in darkness at noon-day and thus not being the chosen. Elder David A. Bednar explained how man becomes "chosen" -

"As we learn in these scriptures, the fundamental purposes for the gift of agency is we are to love one another and to choose God. Thus we become God’s chosen and invite His tender mercies as we use our agency to choose God." (David A. Bednar, "The Tender Mercies of the Lord," Ensign, May 2005, 99)