Did the LDS believe that Christians are doomed to hell?

I am LDS. The LDS church does not teach that all other Christians will go to Hell. We believe that God is a just God and loves all of His children. That He wants all to return unto him. We believe all individuals are judged according to the light and knowledge s/he has received.

The definition of "Heaven and Hell" is a topic of discussion I have been part of. Some individuals interpret Hell to be anywhere one is cut off from the presence of God. Others interpret Hell to be cut off completely from any glory, and are "Sons of Perdition". If you continue to read through my post, I refer to that at the end. With that in mind, I don't know of an official statement about Heaven and Hell in the LDS church.

The doctrine of salvation in the LDS church is quite liberal. We believe there are three degrees of glory one can obtain after this life.

The highest being the Celestial Kingdom. This is the place prepared for those who have “received the testimony of Jesus” and been “made perfect through Jesus the mediator of the new covenant, who wrought out this perfect atonement through the shedding of his own blood” (D&C 76:51, 69). To inherit this gift, we must receive the ordinances of salvation, keep the commandments, and repent of our sins.

The next is the Telestial Kingdom. Generally speaking, individuals in the terrestrial kingdom will be honorable people “who were blinded by the craftiness of men” (D&C 76:75). This group will include members of the Church who were “not valiant in the testimony of Jesus” (D&C 76:79). It will also include those who rejected the opportunity to receive the gospel in mortality but who later received it in the postmortal spirit world (D&C 76:73-74).

The third degree is the Terrestrial Kingdom and is reserved for individuals who “received not the gospel of Christ, neither the testimony of Jesus” (D&C 76:82)

Finally we have Perdition, which is not a Kingdom of Glory. This will be the state of “those who know [God's] power, and have been made partakers thereof, and suffered themselves through the power of the devil to be overcome, and to deny the truth and defy [God's] power” (D&C 76:31).

The statement in question is an unsupported statement made by Rev. Dn. Dr. Brendan Pelphrey in an article he wrote on orthodox Christian theosis and deification in new religious movements, titled, "I said, you are gods." This article was published in Volume No. 13 of the periodical journal, "Spirituality in East and West".

In the exact same publication, a response to Rev. Dn. Dr. Brendan Pelphrey's: I said, you are gods, was also published, titled, "Mormon Deification Compared to Orthodox Christian Theosis." Interestingly, even though this article was written as a response, it was published ahead of Pelphrey's article as the fourth article in the volume, Pelphrey's article was the last.

In, "Mormon Deification Compared to Orthodox Christian Theosis" the authors discuss Rev. Pelphrey's misconceptions and examine his sources, revealing some of them to be anti-mormon.

"Rev. Pelphrey's purpose in writing his essay seems to be to show what Orthodox theosis is and what it is not. Although the Reverend no doubt knows what he is talking about in regard to Orthodox beliefs in this area, his knowledge of Mormonism seems to be very limited.

[...]

... he has made false assumptions and, as a result, many misleading comparisons. His numerous references to "Mormons" and "Mormonism" make it clear that he is primarily comparing his own beliefs with LDS beliefs and his apparent assumption that our doctrine of deification is similar to those of the Eastern religions has lead him to make misleading claims.

[...]

... his misrepresentations of LDS beliefs make it deceptive to other Christians and an affront to members of the LDS faith. In addition to correcting some of Rev. Pelphrey's statements, we will attempt to show that Rev. Pelphrey's concept of Mormon deification and other associated LDS doctrines is erroneous in many areas ...

They then continue to correct all of the misconceptions that Rev. Pelphrey made in his article.

In the LDS view, Christians are not going to hell, as understood by Christians or Mormons. For Protestants, Catholics and Orthodox Christians, hell is the ultimate and neverending punishment after the Last Judgment. This Christian view of hell is what Latter-day Saints call "outer darkness." The LDS belief is that an extremely small number of individuals called "Sons of Perdition" will receive this judgment (D&C 76:43-45). Latter-day Saints believe that none of these individuals will be Christians but will be apostates from the truth who commit the "Unforgivable Sin." We believe that these individuals have to receive the testimony of the Holy Spirit and then -- fully knowing that it is true -- reject it. This is not the case for "Christians." Mormons do believe in another temporary hell which is a subdivision of the spirit world where the spirits of all men go after death to await resurrection and the Last Judgment. Even this hell will not include Christians who lived according to the truths Christ taught."

Though this article clearly illuminates Rev. Pumphrey's erroneous perception of the LDS church, the question of why the Catholic Church would publish selections of Pumphrey's article on their website still remains.

I understand that, today, the LDS Church does not teach that all non-LDS Christians are going to hell. However, in times past, this appears to have been precisely what was taught:

The Book of Mormon indicates that there are only two churches, one true and one of the devil:

"Behold there are save two churches only; the one is the Church of the Lamb of God and the other is the church of the devil; wherefore whoso belongeth not to the church of the lamb of God belongeth to that great church; which is the mother of abominations; and she is the who*e of all the earth." (The Book of Mormon, 1 Nephi 14:10)

It is also pointed out that the establishment of the LDS Church would not have been warranted if Christendom had not been in a state of complete apostasy.

"Nothing less than a complete apostasy from the Christian religion would warrant the establishment of the Church of Jesus Christ of Latter-day Saints." (Documentary History of the Church, Introduction, xl)

From Joseph Smith's testimony, he was told that all creeds of Christendom were not just wrong, but an abomination in the sight of God.

"I was answered that I must join none of them (Christian Churches), for they were all wrong...that all their creeds were an abomination in His sight" (Joseph Smith History 1:19).

Bruce McConkie affirmed that non-LDS Christians would reap damnation.

"Believers in the doctrines of modern Christendom will reap damnation to their souls (Bruce R. McConkie, Mormon Doctrine, p.177)

Other assertions of general authorities are pretty harsh as well:

"...orthodox Christian views of God are Pagan rather than Christian." (Mormon Doctrine of Deity by B.H. Roberts, p.116)

"...the God whom the 'Christians' worship is a being of their own creation..." (Apostle Charles W. Penrose, JD 23:243)

"...all the priests who adhere to the sectarian religions of the day with all their followers, without one exception, receive their portion with the devil and his angels." (The Elders Journal, Joseph Smith Jr., editor, vol.1, no.4, p.60)

"And any person who shall be so wicked as to receive a holy ordinance of the gospel from the ministers of any of these apostate churches will be sent down to hell with them, unless they repent of the unholy and impious act." (Orson Pratt, OP-WA, "The Kingdom of God," no.2, p.6)

"...the great apostate church as the anti-christ...This great antichrist...is the church of the devil." (Apostle Bruce R. McConkie, Mormon Doctrine p.40)

"Both Catholics and Protestants are nothing less than the "who*e of Babylon" whom the lord denounces by the mouth of John the Revelator as having corrupted all the earth by their fornications and wickedness." (Pratt, The Seer, p.255)

"Evil spirits control much of the so-called religious worship in the world; for instance, the great creeds of Christendom were formulated so as to conform to their whispered promptings." (Bruce R. McConkie, Mormon Doctrine, p.246)

"After the Church of Jesus Christ of Latter-day Saints was organized, there were only two churches upon the earth. They were known respectively as the Church of the Lamb of God and Babylon. The various organizations which are called churches throughout Christiandom, though differing in their creeds and organizations, have one common orgin. They belong to Babylon." (George Q. Cannon, Gospel Truth, p.324)

Conclusion

So, historically speaking, it seems clear that Mormon authorities considered all non-LDS Churches as apostate whose members were, in fact, doomed to hell.