Doctrine and Covenants 29 addressed some questions that Church members had about what they had read in the Book of Mormon, namely, about the gathering of Israel, Christ’s Second Coming, and Zion being built in the Americas.
The heading that John Whitmer wrote for this revelation indicates that a group of Church members “enquired of the Lord” about their questions about Zion “and thus came the word of the Lord through Joseph the seer.”
“Section 29,” Steven C. Harper, Doctrine and Covenants Contexts
This is the earliest known revelation to Joseph Smith that uses the term agency and that describes premortal life. It begins by teaching that people actively choose to hear his voice, then explains Satan’s lust for power and how he led away a third part of the host of heaven “because of their agency,” explains how the plan of salvation safeguards agency, and ends with an emphasis on agency, that we grow into agency as we begin to become accountable.
“The Second Coming of Christ: Questions and Answers,” Robert L. Millett, Sperry Symposium Classics: The Doctrine and Covenants
Doctrine and Covenants 29 teaches how the Lord will gather his faithful and that the wicked will burn as stubble, both prominent events in the Second Coming.