Therefore it shall come to pass that whosoever will not believe in my words, who am Jesus Christ, which the Father shall cause him to bring forth unto the Gentiles, and shall give unto him power that he shall bring them forth unto the Gentiles, (it shall be done even as Moses said) they shall be cut off from among my people who are of the covenant. (3 Nephi 21:11)All putative truth must be tested. The severity of judging incorrectly in the case of the one mighty and strong gives pause. In fact, it would seem that those living in the last days would be pressed to find a more worthy focus of their attention than finding out who this person is and isn't, so that they don't miss the boat.
Well, it turns out that the truth paints a slightly different and very important picture.
People from the LDS tradition love the idea of having a "dispensation head." They love being able to put their faith in a man. They love the idea of outsourcing their relationship with God. It doesn't work like that. Salvation can only come through your personal relationship with God. You don't have the option of being saved in some other way. When we find ourselves operating through a mortal mediator, we can rest assured that this is a relationship of cursing rather than blessing.
Those who like the idea of a mortal mediator consider themselves saved in spite of lack of evidence in that regard. They think the default situation is to be connected to God. This is not true. Because of the fall of Adam, our default position is one of separation from God.
18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.[Incidentally, lest you think you do this already, to believe in a scriptural sense means to trust in, adhere to, and obey without reservation or exception.]
19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil. (John 3)
To become and remain connected to him requires persistent effort.
1 I am the true vine, and my Father is the husbandman.How do we connect and remain connected? We obtain and live his word (see John 15:7).
2 Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit.
3 Now ye are clean through the word which I have spoken unto you.
4 Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me.
5 I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. (John 15)
We are in a default state of separation. We connect through obtaining and living God's word. We remain connected as long as we continue to obtain and live God's word.
What happens if, in a connected state, you reject God's word? You disconnect!
It turns out that whenever God delivers his word through a person, those who reject that message will be cut off from the Lord. 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) Inasmuch as your words are his words, the same will be true of you or anyone else. This is why Samuel the Lamanite could say this: "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)
Oh how important it is to obtain and heed God's word, whatever the source.