All light and truth are available to all people, but some people, through their heed and diligence, are much more effective at acquiring it than others. God uses these people to make further light and truth available to everyone else. Even those who are zealous in their obedience to God can require truth from other people in order to reach the next level of light and truth. Though Paul was zealously faithful to the light and truth he had inherited as a Pharisee, he rejected the Christian message from Jesus’ disciples. As part of his path forward, he was required to visit one of the preachers he had previously rejected to obtain a miraculous healing. He had previously ignored evidence of the higher truth possessed by the Christians, and had God not intervened with an unusual miracle, he would have permanently cut himself off from considerable progress towards God.
As we see in scriptural examples, the common response to people who possess greater light and truth is negative. For example, Paul was surrounded by Christians who were demonstrating powerful gifts from God accompanying their heretical teachings of the Lord Jesus. Instead of investigating it, he actively persecuted them.
We are accountable for all truth, from all people. There will be far more people who suppose they have greater light and truth than those who actually do . All putative truth must be tested. All new truth will be different, although all different ideas are not necessarily true. One can comprehend truths that lie below their understanding, but they cannot tell out of hand whether putative truths higher than they possess are true or not.
When we encounter anyone who has more light and truth than we do, our objective is to obtain all they have, become as close to God as they are, and then go find more light and truth elsewhere. When you encounter someone who possibly has more light and truth than you have, you should investigate it further. What you will probably do, though, is persecute, ignore, or reject that person. That which is different should never be dismissed out of hand.
Whenever God delivers his word, directly or through another person, those who reject that message will be cut off from the Lord until and unless they humble themselves and repent. This is why Nephi was told “Inasmuch as they will not hearken unto thy words they shall be cut off from the presence of the Lord. And behold, they were cut off from his presence.” (2 Nephi 5:20) This is equally as true for anyone who shares with you any truth that is beyond what you possess.
Oh, how important it is to obtain and heed God's word, whatever the source. All who hear the word of God from any source and on any topic ought to heed the warning of the unlikely prophet, Samuel the Lamanite:
Therefore repent ye, repent ye, lest by knowing these things and not doing them ye shall suffer yourselves to come under condemnation, and ye are brought down unto this second death. (Helaman 14:19)