In the first books of the Book of Mormon, we get an intimate look into the struggles and triumphs of a family with conflicting ideas of what life is about, and how to live it. Lehi and Nephi are the spiritual stalwarts, and willing to endure whatever they must to follow the Lord. Laman and Lemuel can’t understand that attitude, and value comfort – which they’re definitely not getting on this journey – and the things they’re familiar with. They seem to have lived their lives so far becoming skilled at the things that aren’t eternally important, and which don’t help them enough on this quest the Lord has sent them on. It’s the skills which Lehi, Nephi and Sam have developed which are the most useful here. There’s a message in there for us!
Because they hadn’t developed those skills, which were so needed to endure this journey, Laman and Lemuel constantly relied on others’ knowledge of spiritual things. So they never had enough to keep them consistently humble or righteous – to bind them to God, and allow their better natures to grow and win. Eventually, their darker natures overcame any light that was in them – to the extent that they wanted to murder their own brother and father. They never found out for themselves, direct from God, like Nephi did – from the beginning.
This is what President Nelson meant, I believe, when he said that “in coming days, it will not be possible to survive spiritually without the … constant influence of the Holy Ghost.” Borrowed light is never enough. Those better and darker natures are at war within us, and the work of our mortal lives is to feed the light; make it strong enough to overcome the dark in us, or the desire for darkness. That’s why we need the Holy Spirit to sanctify us, bit by bit. Knowing the religious facts, knowing what’s right, hearing it from faithful others, can’t do that. The light of heaven/goodness/our better natures/Christ needs to be becoming stronger and stronger in us all the time.