Note that in laying out the evidence below I am not in any way advocating modern polygamy. I am also not arguing that the ideas below should be taught today as Mormon doctrine. This is only meant to show that original Mormonism was different from what is taught today in the modern LDS (Brighamite) Church. I am only presenting this information for its historical value as evidence that Mormonism after 1840 and up until about 1900, had grown into a more Indo-European religion in its rejection of the Pauline and Augustinian ideals of celibacy with its radical pendulum swing in the opposite direction: toward the doctrine of procreating male God-kings spreading their seed through wives and concubines. As I see it, neither extreme (celibate priests or polygamist priests) is healthy or ideal in our modern society. In other words, neither the body-despising Pauline ideal of celibacy nor the male-centered Nauvoo era LDS doctrine -- of accumulating wives to prove your worthiness for future godhood -- is ideal in today's world. Having said that, I'm not going to shy away from explaining below why polygamy was actually practiced in the Mormon Church for nearly a 100 years!
Did early Mormon Prophets and Apostles teach the doctrine that plural marriage was necessary for the highest degree of glory in the celestial kingdom? Let's start with what Joseph Smith, the Prophet of the Restoration, had to say. According to Joseph's scribe Willam Clayton:
“ … [Joseph Smith taught that] the doctrine of plural and celestial marriage is the most holy and important doctrine ever revealed to man on earth, and that without obedience to that principle no man can ever attain to the fullness of exaltation in the celestial glory.
Source: William Clayton, Joseph Smith’s secretary, Historical Record, vol. 6, page 226
What we see below is the idea was that you had to be a polygamist in order to attain the highest exaltation among the Gods (see Abraham 4 on the Gods). This is because for an LDS Priest, becoming a God means growing his "talents," meaning spreading his seed kind of like compound interest; only in this case you are investing your seed into wives and concubines who produce your offspring; for they are given to the man in order to "bear the souls of men" (D&C 132: 63): wherein the sperm/seed of the male body is the priesthood per Abraham 2:11; and so "priesthood power" is procreation-power, i.e. the male seed creating lives (see D&C 132: 19-22); the lives are future progeny that become for the future human-turned-god, an expansion of his future kingdom. Being a god is to be a king over a kingdom with wives and concubines and servants (see D&C 132: 19-22, 37-63): in order to expand one’s kingdom thought all eternity. This is why LDS temples end with a reference to one's loins and their posterity. Becoming a god was thus modeled after Israelite kings like King David depicted below:
The images above is from King David’s Love Life: How Many Wives Did David Have? by Ana Coteneanu. As she writes in her article:
The Royal Harem: How Many Wives and Concubines Did David Have?
By the time David was ruling in Jerusalem, he had what was essentially a royal harem—dozens (if not hundreds) of women in his household. But this wasn’t just about romance or attraction. In ancient kingdoms, having a large harem was a status symbol. The more wives and concubines a king had, the more powerful he appeared. ...
It is clear that Joseph Smith saw himself as a modern day Israelite King and thus he felt he was justified in basically forming a kind of "royal harem" like King David did. As Smith begins D&C 132, verse 1 with: "I, the Lord, justified my servants Abraham, Isaac, and Jacob, as also Moses, [King] David and Solomon, my servants, as touching the principle and doctrine of their having many wives and concubines ..." Smith then dictated the following in verses 37-39:
37 Abraham received concubines, and they bore him children; and it was accounted unto him for righteousness, because they were given unto him, and he abode in my law; ... and because they did none other things than that which they were commanded, they have entered into their exaltation, according to the promises, and sit upon thrones, and are not angels but are gods.
38 [King] David also received many wives and concubines, and also Solomon and Moses my servants, as also many others of my servants, from the beginning of creation until this time; and in nothing did they sin save in those things which they received not of me.
39 [King] David’s wives and concubines were given unto him of me [God], by the hand of Nathan, my servant, and others of the prophets who had the keys of this power; ...
Just as Israelite Kings grew in wealth, wives, status, and power, Joseph Smith sought to mimic their reign and glory: basically calling such a lifestyle the way of all the Gods themselves.
Accumulating Mormon wives thus became a sign of the way of the Gods, a kind of divine recipe on becoming powerful like a god through kingdom building. Smith taught that the Gods accumulated wives and we should as well. On page 18 of An Intimate Chronicle: The Journals of William Clayton, edited by George D. Smith, we read:
In support of Clayton’s second marriage, Smith assured him: “You have a right to get all you can.”[41] Shortly afterward the prophet refused Clayton permission to marry Lydia, the third Moon sister, citing a revelation “he had lately, [that] a man could only take 2 of a family.” Smith then asked if Clayton would “give L[ydia] to him.” Lydia Moon refused Smith’s offer because she had promised not to marry while her mother lived.[42]
Footnote 41 reads:
Journal 2, “Nauvoo, Illinois,” August 11, 1843. In Appendix C, “William Clayton’s Testimony,” Clayton quotes Joseph Smith as saying, “It is your privilege to have all the wives you want.” Smith also once reportedly explained: “The result of our endless union will be offspring as numerous as the stars of heaven or the sands of the seashore” (HC 5: 391-92). Compare Journal 2, “Nauvoo, Illinois,” May 16, 1843.
Add to this the fact that Smith's revelation on plural marriage covered in D&C 130, 131, and 132, clearly argues that only those humans who enter into the Mormon practice of plural marriage, become gods in the highest level of the celestial kingdom of glory; for the virgin wives and concubines are given unto the polygamous male (section 132 explains) in order for him to have an increase of progeny via his seed/sperm (see Abraham 2:11); and thus through his seed implanted into multiple wives and concubines, he is able to bear the souls of men: through earthly and celestial polygamy which glorifies God the Father (as if God is a proud grandfather of his expanding grand kids through the practice of polygamy).
This is why one of the earliest Mormon diagrams is Orson Hyde’s Kingdom of God Diagram, representing a polygamous male's ascending personal kingdom of added wives like rungs on a ladder leading to his exalted kingship, just like God the Father. To read Hyde's comments on his diagram see here or here.
On Talents
Note that Smith described the practice of plural marriage to Nancy Rigdon in terms of entering into the practice as one of his wives or concubines being akin to the parable of the talents. Smith says to Nancy (footnotes from The Joseph Smith Papers) regarding her becoming his next plural wife:
... in obedience [to the law of plural marriage] there is joy and peace unspotted, unalloyed, and as God has designed our happiness, the happiness of all his creatures, he never has, he never will, institute an ordinance, or give a commandment to his people that is not calculated in its nature to promote that happiness which he has designed, and which will not end in the greatest amount of good and glory to those who become the recipients of his laws and ordinances. Blessings offered, but rejected, are no longer blessings, but become like the talent hid in the earth by the wicked and slothful servant [see Matthew 25:25–26]—the proffered good returns to the giver, the blessing is bestowed on those who will receive, and occupy; for unto him that hath shall be given, and he shall have abundantly; but unto him that hath not, or will not receive, shall be taken away that which he hath, [Matthew 13:12]or might have had. ...
Note that this aligns with D&C 132, wherein those who marry as polygamists have an increase of lives (progeny) through the male seed implanted in many wives and concubines ("given unto him"); while those who reject the law of polygamy are not "blessed" with celestial progeny (the ability to produce "eternal lives"), but remain permanently celibate in heaven without an "increase," i.e. without the ability to reproduce in heaven; thus, they remain without "blessings" because they basically "hid their talent" when on earth by refusing to practice plural marriage.
Orson Hyde, who was eventually polygamous himself, clearly understood this idea that becoming a polygamous male was like investing your "talent" wisely, in this case "talent" meant investing your "seed" by forming a kingdom of earthly wives that grows you a kingdom of progeny. As Hyde explains his diagram by stating:
.... he that has been faithful over ten talents, shall have dominion over ten cities, and he that has been faithful over five talents, shall have dominion over five cities, and to every man will be given a kingdom and a dominion, according to his merit, powers, and abilities to govern and control. It will be seen by the above diagram that there are kingdoms of all sizes, an infinite variety to suit all grades of merit and ability. The chosen vessels unto God are the kings and priests that are placed at the head of these kingdoms.
Again, compare this to D&C 132, that basically teaches that those Mormons who are exalted are those who are basically wise with their "talents," i.e. they accumulate wives and concubines by practicing polygamy in order to gain exaltation and eternal lives (progeny) which grows one's kingdom; while those who do not practice polygamy, squander their talent (the ability to implant their seed/sperm into wives to grow a kingdom, see Abraham 2:11; D&C 132: 19-21, 37-39, 63) and in the afterlife lose the chance for the highest degree of celestial glory, and thus remain separate and single, i.e. celibate (without an increase of celestial progeny in the eternities), see D&C 132: 15-17; because to increase one's seed in the heavens as a god, they had to have entered into the law of plural marriage on earth: where they would have learned how to exercise their sphere of influence and acquire a kingdom of wives and concubines, which could prepare them for godhood and the role as a kingly god reproducing celestially in heaven via heavenly plural marriage; which would build new worlds and kingdoms of endless offspring to rule over as a god (which is the way of all the Gods as Joseph Smith explains in the King Follett Discourse and the Book of Abraham chapters 2-4).
In Journal of Discourses, Volume 13, Discourse 22 on Celestial Marriage, Apostle Orson Pratt clearly teaches this as well. Here is what Orson Pratt says in his book The Seer (emphasis added):
God raised up Solomon to sit upon the throne of Israel; and He appeared unto him twice and gave him great wisdom above all others and the Lord was with him, and magnified him exceedingly before all Israel, and hearkened unto his prayer and filled the temple which he built with a cloud of glory, and caused fire to descend from Heaven to consume the sacrifice. [95] This great man was much better calculated to train up children in the way that they should go than any other man living, for God had given him greater wisdom; hence he had seven hundred wives and three hundred concubines (1 Kings 11). But even this wise man, turned away from the Lord, by taking wives from among surrounding nations who were idolaters which thing the Lord had expressly forbidden (see verses 1, 2). Solomon was not condemned for marrying many wives of his own nation; but having transgressed the strict commandment of God in marrying out of his nation, he was left unto himself and turned away after the idolatrous gods of his wives; and God rent the kingdom in twain in the days of his son, and gave ten tribes to another not of his seed.
Thus it will be seen that even among the people of God there are some who are more worthy than others, consequently God gave such more wives and children than He did to others. These blessings were dispensed, like all other blessings, according to the righteousness, wisdom, faith, holiness and qualifications of those who professed to be the people of God. Some receiving more; some less; some none at all; and some having taken from them even those they had received.
Therefore though the males and females had been of equal number in Israel, yet God would confer upon some more than upon others, according to their worthiness. As it was among Israel, so it is among the people of Utah. Some are entitled to a greater number of wives than others, because of their righteousness. Though the census should show an equal number of the sexes in that Territory, that does not prove that all the men are equally qualified to instruct, counsel, govern, and lead wives and children in the paths of righteousness. A father would not confer upon his children equal blessings, authority, and power, unless they were equally faithful. A wise king having many sons would confer authority and power upon [96] such only as would use the same for the benefit of the people. Those who would not be subject to good laws themselves, he would not entrust to govern others. Our Heavenly Father acts upon the same principle. He is willing that all should enjoy equal rights and privileges, upon the ground of equal obedience. We have this illustrated in the parable of the talents: one having one; another two, and another five. Those who made a proper use of what was entrusted to them, gained more: those who made an improper use of their blessings, lost all they had: their blessings were taken from them and given to others, who had more abundantly. This explains the mystery why the Lord in ancient times gave more wives to one than what he did to another, when to all appearance the number of males and females were about equal. ...
... The continuation of the name and posterity of a righteous man was considered a great blessing; hence David exclaims before the Lord, saying: “The children of thy servants shall continue, and their seed shall be established before thee.” (Psalm 102:28). To have the chain of posterity broken by death was considered a great calamity, therefore the Lord made strict provisions for such cases. ...
Brigham Young also uses the analogy of a talent to describe a man marrying polygamously. As this person online explains:
Brigham Young's sermon (1873) detailed role of non-polygamists in the Celestial Kingdom—as servants. Mormon polygamy seems very misogynistic—ah, but I repeat myself.