I know it's different than most Christian faiths' beliefs, and I know the missionaries teach it... I know it's a big part of Mormon curriculum and doctrine, and this site is replete with questions about seemingly every part of it, but would someone connect the dots and piece it together here in an overall summary? Why is it needed in LDS doctrine, what questions does it answer?
The LDS Plan of Salvation can be found on the official LDS website here.
In summary, the following are the main points:
This, of course, only scratches the surface, and the LDS Plan of Salvation encompasses not only salvation, but exaltation.
The most basic LDS explanation of what Salvation is:
There are actually six definitions of Salvation in LDS theology, all defined here. (Click the "view more" link.)
A somewhat shorter version than the one linked to at the beginning of the article can be found here.
As for how one achieves Salvation, the teaching differs from mainstream Christianity. Whereas the vast majority of Christianity believes that salvation is by Faith alone, with no works attached, LDS teaching is different. In LDS theology, only General Salvation is attained through Faith in Christ alone.
Assistant to the Council of the Twelve July 1972:
So the general salvation is through faith in Christ alone, but that's just the beginning. There are, in Salvation, more than one level of Glory, which is, as stated above "conditioned not only upon grace, but also upon obedience to gospel law.".
However, this is not seen within LDS teaching as a works-based salvation, even at this level. There is somehow, in LDS theology a difference between obedience, and earning your way in. More from the article quoted above expands upon this.
But later on in the article, Burton again teaches that works are a result of faith. But the fact remains that in LDS theology, works are required. Perhaps not as a way of "buying" our way in, but as a sign, in that, if we don't have works, it's a sure sign that we don't have faith. Often, the following is quoted as support for this belief.
And also, the lack of good works/righteousness as a sign of not really being Faithful is stressed in Matthew 15:8, which is heard in almost every Sunday School class I attended when I was attending the LDS Church.
Burton goes on to define those works:
Burton expands a bit on those who do not obey the Law in full:
This is the opposite of Mainstream Christianity, which believes that as imperfect beings, we cannot be fully obedient, and thus is the distinction - the splitting of hairs between the "mainstream" understanding of "by faith alone". Mainstream Christianity says "I can never be good enough to add a single iota to my salvation. I am miserable and wretched, and I rely solely on God's mercy because even my righteousness is as filthy rags to Him." The LDS teaching, on the other hand, is that we must be fully obedience, and we are able to be fully obedient, and those that achieve this attain the highest form of exaltation.
It's hard to follow after David's very good, exhaustive answer, but here is a different approach, which emphasizes more the procedural flow of it as a literal "plan" (David's first few bullet points).
My answer is a summary, or in some cases, a re-statement, of what is found in the LDS missionary manual, Preach My Gospel (Chapter 3, Lesson 2). All references and/or quotes would point there.
The Plan of Salvation is God's plan for the salvation of His children (us). The Plan of Salvation has been on the earth whenever the Gospel of Jesus Christ is revealed in its fulness. It answers three main questions:
LDS theology teaches that the fulness of the Plan of Salvation is in the Bible and Book of Mormon together: that one without the other is, in a sense, incomplete.
We are God's children. We lived with God as spirits before we came to earth. We weren't like God, because we didn't have the glory, experience, and power that He has. Since God loves all His children, and is in fact our heavenly parent, He wants us to "grow" and become like Him.
In the center of God's plan is Jesus Christ, who would suffer the Atonement to redeem each of us so that we may return to live with God, and be like Him, to have immortality and eternal life. We chose to accept this plan before we came to Earth.
Of course, Satan (the devil) is an enemy to God's plan. He rebelled and was cast out. We were given agency in our pre-mortal dwelling, which is the free will, or power, to choose. We must choose to follow Christ or follow Satan. Since we chose to come to earth and accept God's plan, we would be separated from His presence for a very important purpose.
To carry out the plan, Jesus Christ created heaven and earth, as a place for us to come and be separated from God's physical presence, where we would forget our pre-earth life, gain experience and learn to walk by faith and not by sight. The creation was for us (and God's joy), and it is one of the most glorious events of eternity.
Adam and Eve
God placed Adam and Eve on the earth, in the Garden of Eden, as the first two of His children to obtain physical bodies. They had agency, and lived in God's presence, but were innocent while in the garden. They did not know good from evil.
They were commanded to multiply and replenish the earth. God also commanded Adam and Eve to not eat of the fruit of the tree of knowledge of good and evil. While they obeyed this commandment, they could live in God's presence, but they could not progress by experiencing opposition. They couldn't be happy because they couldn't be sad in contrast.
Well, we all know what comes next. Adam and Eve were tempted by Satan to eat the forbidden fruit, and they did so. They were cast out of God's presence, and became subject to death: physical death, which means that their bodies would eventually die, and spiritual death, or separation from God. This is called the Fall, and it is vital to God's plan, and was no surprise to God. (The Atonement was prepared to redeem men from it.)
Adam and Eve could now choose between good and evil (they now had moral agency), which means they could learn and progress spiritually, and continue to carry out the plan. They could also have children, so the rest of God's spirit children could obtain bodies and come to earth.
They were taught the gospel, so they could know of Jesus Christ and the Atonement which would be to come. Thus, they were able to repent.
Here in mortality, we have great opportunities and blessings to learn, gain valuable experience which we could have no other way, and eventually become like our Heavenly Father.
Our experiences here should teach us and our righteous choices will bring us joy. Following God's path and commandments will bring us happiness, whereas following Satan's temptations will draw us away from God and bring us sorrow.
We have two major obstacles to overcome while here. One is physical death: God has a perfect, glorified physical body, and we must have one to be like He is, and it must never die. The other is spiritual death (sin): we make mistakes here on earth because we are tempted by Satan, and because we are out of God's presence, the flesh is subject to carnal nature. We cannot overcome either by ourselves.
We must follow and accept the gospel of Jesus Christ in its fulness, by having faith, repenting, being baptized, receiving the Gift of the Holy Ghost, and enduring to the end. But even that would not be enough without Jesus Christ.
Jesus Christ came in the meridian of time to accomplish what is the most significant, important, earth-shattering (literally) event in all of history: the Atonement.
Since we cannot become like God on our own from our fallen state (with sin and death), we need not only a perfect example to follow, but we also need a Redeemer who can save us from both sin and death. Jesus Christ was chosen in the pre-mortal life to perform the Atonement.
To save us from death, Christ laid down His life on the cross and suffered (a vile form of) death. He was then resurrected, which loosed the bands of death and opened the gate for all others to be resurrected. All who have lived on Earth -- past, present or future, good or evil -- will eventually be resurrected and receive a perfect, glorified, immortal body of flesh and bone, thanks to the Savior's resurrection.
We also need to be saved from sin. The Atonement covers this as well. Christ paid the penalty of sin for all of us so that we can accept His terms and be forgiven, and made as new. Of course, it doesn't mean we don't have responsibility: we must follow His gospel, and then through the Atonement we can return to live with God.
As we die, our bodies and spirits separate. Our spirits go to a place known as the Spirit World. This is a necessary part of God's plan, since we must be transformed from mortality to immortality. It doesn't change who we are, our desires for good or evil, or our personalities, it is simple a change of state from physical to spiritual.
For those who lived good, respectable lives, it is a sweet experience, and they will live in joy and happiness, and have rest from their troubles and sorrows. Those who chose not to obey the gospel or lived lives contrary to it (and did not repent) will be consigned to a state of misery and pay for their sins. The gospel is preached to all who did not receive it on Earth. (This is the purpose for LDS temple and family history work.)
Resurrection and Judgment
Eventually, all will be resurrected: their physical bodies will re-unite with their spirits never again to be separated. This is a mercy of the Atonement, and will be given first to the righteous, then later to the wicked. Through this, we overcome physical death. This is immortality, but not necessarily eternal life, which is living immortally in the presence of God. (This is not re-incarnation.)
We will be judged and rewarded "according to our works and our desires." (to quote PMG). Eternal life is granted to those who do all that is required of them and live their lives such that they earn exaltation, which is living with God in eternal families. This is knowing God and Jesus Christ, and being like them.
Kingdoms of Glory
Depending on how we lived our lives, we will be given an eternal abode in one of the three kingdoms of glory. Essentially, our bodies will resurrect and inherit a glory compatible to how we lived and who we have become, thanks to Jesus Christ.
It's good to note that each individual will be comfortable with the kingdom which they obtain, since that is the quality of life they chose to live. (For instance, a beggar would not be comfortable in a mansion! -- that's not an LDS analogy, that's my own comment.)
The lowest level of glory is called the Telestial Kingdom. It is compared to the glory of the stars (which are nice to look at, but don't emit much light; they don't illuminate). People who "continued in their sins and did not repent in this life" will be rewarded here (which, it's said, is still more glorious than this earth is currently).
People who lived good lives but did not accept the fulness of the gospel will inherit the Terrestrial Kingdom, compared to the glory of the moon.
But those who lived good lives, and did accept the fulness of the gospel, who were washed of all their sins, will live with God and Jesus Christ in the Celestial Kingdom. Those who qualify for exaltation through the new and everlasting covenant of marriage (eternal marriage in a temple) will receive the highest degree in the Celestial Kingdom, and literally become like God, and have all that He has. This reward is achieved by making and keeping sacred covenants. These will receive a fulness of joy.