Of all the qualities discussed in the Beatitutes, the meaning of the term poor in spirit is the least obvious. Although a simpler term could have been rendered, the term poor in spirit contrasts the richness of the blessing received, for theirs is the kingdom of heaven as heirs of God, and joint-heirs with Christ (Rom 8:17). Therefore, all that my Father hath shall be given unto him (DC 84:38). But blessed are the poor who are pure in heart, whose hearts are broken, and whose spirits are contrite, for they shall see the kingdom of God coming in power and great glory unto their deliverance; for the fatness of the earth shall be theirs (DC 56:18).
The poor in spirit are not "spiritually poor" or bereft of spiritual attributes. Rather, the term means to be humble, submissive, spiritually dependent, and penitent—in effect those who are poor in spirit have a broken heart and contrite spirit.
Robert E. Wells
"To be poor in spirit means to be humble, teachable, contrite, meek, obedient. As the Phillips Modern Translation states, the meek are those who 'know their need for God.' To be poor in spirit is to recognize that we are not self-sufficient spiritually (or materially, for that matter), but rather that we are always in debt to our Heavenly Father, from who all blessings flow. In fact, our posture before our God is as the needy, even as beggars. President Harold B. Lee spoke on this subject in the following way:
"To be poor in spirit is to feel yourselves as the spiritually needy, even dependent upon the Lord for your clothes, your food, the air you breathe…It is indeed a sad thing for one, because of his wealth or learning or worldly position, to think himself independent of this spiritual need. [Poor in spirit] is the opposite of pride or self-conceit. To the worldly rich it is that 'he must possess his wealth as if he possessed it not' and be willing to say without regret, if he were suddenly to meet financial disaster, as did Job, The Lord gave, and the Lord hath taken away; blessed be the name of the Lord (Job 1:21). (Stand Ye in Holy Places, pp. 343-4)" (Robert E. Wells, The Mount and the Master, pp. 4-5)
Jeffrey R. Holland
"…the Book of Mormon sermon added the phrase 'who come unto me…' Obviously in the 3 Nephi rendering, being poor in spirit is not in itself a virtue, but it will be so if such humility brings one to claim the blessings of the kingdom through the waters of baptism, making covenants, and moving toward all the promises given to covenant-making disciples. It is significant that the phrase 'come unto me' is used at least four more times in the twenty or so verses that follow this one." (Christ And The New Covenant, p. 263)