The word of God is crystal clear in stating that liars are thrust down to hell. This is no arbitrary punishment. Liars by definition are those who refuse to reconcile their lives to what they know. Those in this state cut themselves off from the improvement necessary to prepare for judgment.
Awareness of truth in and of itself is not the same as our reconciliation to it. Any time our character deviates from our sincere understanding of God’s character, we are out of harmony with God, and in rebellion: “Wherefore, let every man beware lest he do that which is not in truth and righteousness before me.” (D&C 50:9)
Going against the light is rebellion against God:
5 This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all.
6 If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:
7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin. (1 John 1)
There is no such thing as grades of rebellion. Rebellion in even one thing makes you rebellious in all (see James 2:10).
Rebellion against God is the one and only problem in this world. Anyone who is fully reconciled to God will be saved, no matter how much light they may have. The quantity of light determines the degree of glory, not the state of salvation. You are either saved or you are not, but there are infinitely many glories, which are as diverse as the knowledge possessed by each person.
You can’t rebel against God in this life and dwell in his presence without first passing through the fires of hell, no matter how much light you have or don’t have. If we knowingly act contrary to our understanding of God’s will, we are in open rebellion against God; we are cut off from God and will be forever until we repent.
But behold, and fear, and tremble before God, for ye ought to tremble; for the Lord redeemeth none such that rebel against him and die in their sins; yea, even all those that have perished in their sins ever since the world began, that have wilfully rebelled against God, that have known the commandments of God, and would not keep them; these are they that have no part in the first resurrection. (Mosiah 15:26)
But behold, ye have rejected the truth, and rebelled against your holy God; and even at this time, instead of laying up for yourselves treasures in heaven, where nothing doth corrupt, and where nothing can come which is unclean, ye are heaping up for yourselves wrath against the day of judgment. (Helaman 8:25)
Some seek to excuse themselves in willful disobedience by claiming that the blood of Jesus will save them in spite of their sin. Jesus cannot save his people in their sins. He can only save them from their sins.
And, in fine, wo unto all those who die in their sins; for they shall return to God, and behold his face, and remain in their sins. (2 Nephi 9:38)
And I say unto you again that he cannot save them in their sins; for I cannot deny his word, and he hath said that no unclean thing can inherit the kingdom of heaven; therefore, how can ye be saved, except ye inherit the kingdom of heaven? Therefore, ye cannot be saved in your sins. (Alma 11:37)
The importance of reconciliation to the light you have is immeasurable. Any degree of rebellion means you are under the control of Satan. He motivates you. He will use you to hurt those around you who try to turn to the light, and you won’t even notice it. You’ll just notice that you are angry at them (see 2 Nephi 4:13; 28:19-20). You will unknowingly go around tempting people to turn away from the light, and you won’t even realize it.