The doctrine in D&C 76 on the telestial is plain enough, but not often taught:
D&C 76:98 And the glory of the telestial is one, even as the glory of the stars is one; for as one star differs from another star in glory, even so differs one from another in glory in the telestial world;
99 For these are they who are of Paul, and of Apollos, and of Cephas.
100 These are they who say they are some of one and some of another—some of Christ and some of John, and some of Moses, and some of Elias, and some of Esaias, and some of Isaiah, and some of Enoch;
I remember an instructor at BYU who understood those verses, but didn't dare actually state their meaning. He only made reference to it. But they are pretty clear. When it says "these are they who are of Paul, and of Apollos, and of Cephas,... some of one and some of another,...." it is specifically referring to the many different Christian religions. It is saying that the various Christian religions are, speaking as a group, heading toward the telestial kingdom.
Not terribly popular I admit, but, come on. It is pretty plain.
101 But received not the gospel, neither the testimony of Jesus, neither the prophets, neither the everlasting covenant.
The testimony of Jesus here is the testimony of Christ as he is. It is a testimony of the true church. That is why it goes hand in hand with receiving the prophets. Those who receive his servants receives him. That is also why it is equated with receiving the everlasting covenant. The testimony of Jesus goes hand in hand with a testimony of his gospel.
102 Last of all, these all are they who will not be gathered with the saints, to be caught up unto the church of the Firstborn, and received into the cloud.
103 These are they who are liars, and sorcerers, and adulterers, and whoremongers, and whosoever loves and makes a lie.
If we know someone who is a liar, a sorcerer, an adulterer, a whoremonger do we expect they will not receive the telestial kingdom? Of course they will receive exactly what the Lord has stated unless they truly repent. Saying that is not taking judgement from God, it is leaving judgement in his hands instead. It is simply having faith in his word, and no one is condemned for believing him, but they are condemned for unbelief. Amulek put it well:
Alma 11:36 Now Amulek saith again unto him: Behold thou hast lied, for thou sayest that I spake as though I had authority to command God because I said he shall not save his people in their sins.
37 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.
Continuing with the vision of the Telestial:
D&C 76:104 These are they who suffer the wrath of God on earth.
This is a fascinating teaching. We know the telestial suffer the wrath of God in hell, but do we realize they suffer the wrath of God on earth? When men and women are immoral do we realize the Lord is angered by that and they will not escape until they have paid the uttermost farthing? Are we willing to accept that the telestial suffer the wrath of God on earth, as well as in the spirit world?
And rightly so, because wicked men suffer his wrath, but that wrath may in time bring them to repentance. Isn't it wise that God punishes the telestial during the days of their probation?
105 These are they who suffer the vengeance of eternal fire.
106 These are they who are cast down to hell and suffer the wrath of Almighty God, until the fulness of times, when Christ shall have subdued all enemies under his feet, and shall have perfected his work;
Not only is God's wrath on earth used to bring men to repentance, but that it is applied until they are brought to repentance in the afterlife. That is what it means that they "suffer the wrath of God until Christ shall have subdued all enemies under his feet". They suffer the pains of hell until they have fully repented and have paid in a measure for their own sins. When they have repented, when the cup of suffering is full, then Christ will have subdued all enemies under his feet.
And this is an important point. They suffer until they have repented and paid for their sins and that is related to the phrase "and [Christ] shall have perfected his work" that finishes the verse. The point is that at the end of that they will be penetent and willing to accept Christ as their king (otherwise, they have no right in one of his kingdoms). In that state of penitence they can then be baptized in time and receive the gift of the Holy Ghost. Otherwise they could not enjoy the Holy Ghost in the telestial kingdom as God has promised. Without the Holy Ghost, they could not belong to his kingdom for the Holy Ghost can dwell in the hearts of men. Where the Holy Ghost is not, there is no kingdom of God, not even a telestial one, for God cannot dwell in the hearts of men without it. But you cannot gain the Holy Ghost without the ordinance being done for you in this life or the next, and you cannot accept the ordinance without repentance and baptism, be it in this life or the next.
107 When he shall deliver up the kingdom, and present it unto the Father, spotless, saying: I have overcome and have trodden the wine-press alone, even the wine-press of the fierceness of the wrath of Almighty God.
Notice that he presents the telestial kingdom "spotless". How is that possible? Because they have suffered the price for their own sins, they have repented and been baptized and thereby become part of God's kingdom.
108 Then shall he be crowned with the crown of his glory, to sit on the throne of his power to reign forever and ever.
109 But behold, and lo, we saw the glory and the inhabitants of the telestial world, that they were as innumerable as the stars in the firmament of heaven, or as the sand upon the seashore;
110 And heard the voice of the Lord saying: These all shall bow the knee, and every tongue shall confess to him who sits upon the throne forever and ever;
Again, how will they bend the knee? Because they will, after having truly repented of their sins and obtained forgiveness in hell, accept Christ as their Savior and King. Without accepting Christ as king, they cannot become part of any of his kingdom, not even the telestial part.
111 For they shall be judged according to their works, and every man shall receive according to his own works, his own dominion, in the mansions which are prepared;
112 And they shall be servants of the Most High; but where God and Christ dwell they cannot come, worlds without end.
And again, how are they his servants? Because they have been baptized, become part of his kingdom, and received the gift of the Holy Ghost.