I don’t think that this is an accurate observation about Mormonism. LDS doctrine makes plenty of room for the salvation of “infidels”– a person my compare the absolutism in both religion’s claim to correct doctrine and the consequent implications that their method of salvation is the only valid one, but “cannot be saved” is not part of Mormon theology in any way.

Here is some comparisons from http://www.mormonapologetics.org/index.php?showtopic=8088&st=0

Islam sprang out of a fervent and fractious time of religious ferment among Christian and pagan sects just outside the eastern frontier of Europe.

Mormonism sprang out of a fervent and fractious time of religious ferment among Christian sects on the American frontier (you could say just outside the western frontier of Europe).

Islam’s founder, Muhammad, went to a cave to pray and ask God which of the many diverse and fractious Christian faiths in his time and place was true.

Mormonism’s founder, Joseph, went to a grove to pray and ask God which of the many diverse and fractious Christian faiths in his time and place was true.

Muhammad received a “First Vision,” a heavenly visitation from God himself (Allah) in which God told him all the sects were false and an abomination in the eyes of God, and Muhammad was the prophet chosen of God to usher in the last dispensation.

Joseph received a “First Vision,” a heavenly visitation from “God the Father” and Jesus themselves, in which God told him all the sects were false and an abomination in the eyes of God, and Joseph was the prophet chosen of God to usher in the last dispensation.

Muhammad generated Islam’s own unique canon of scripture, which built on the Jews’ ancient canon, even recognizing Abraham, Moses, Jesus et al., as great men in their own right, though traditional Judeo-Christian theology represented a corruption of God’s original pristine religion.

Joseph generated Mormonism’s own unique canon of scripture, which built on the Jews’ ancient canon, even recognizing the Abraham, Moses, et al., as great men in their own right, though traditional Judeo-Christian theology represented a corruption of God’s original pristine Church. (Harold Bloom calls the D&C the closest thing out there to the Koran in style, format and tone, although the D&C is more prosaic, he says.)

While, unlike Islam, Mormonism does not reject Jesus as the Son of God and expiator of our sins, it diverges materially from other sects who regard themselves as Christian as regarding Jesus as separate from (and therefore by necessary implication subordinate to) God the Father as did Arianism. Mormonism’s concept of the Godhead is regarded by virtually all if not all other established Christian sects as the ultimate heresy.

Both religions regard their founding “Prophet” as at the right hand of God, and next to God (and in the Mormons’ case Jesus too), the greatest of all beings.

Both religions regard their respective creeds to be “revelation” received by the “Prophet”; therefore, those outside the faith are strictly infidels who cannot be saved. This aspect of both religions’ creed is absolute and unyielding. For example, there is no acknowledged long term evolutionary process by which the religion came into being through writings and inspiration on the part of the “Fathers of the Church” or other inspired leaders such as Luther and other men who built on their works such as Augustine or Calvin.

Both religions took root and became institutionalized amid nomads, during a period of wandering in the wilderness.

Both religions sharply segregate the sexes during their most sacred ceremonies.

Both religions are reputed to relegate women to a subordinate status to men, throughout their respective cultures.

Both religions eschew, and are repelled by, European intellectual traditions, materialism, androgenous culture, and Classical (i.e., Roman) foundations, to which they acknowledge no debt.

The scriptural canons that are unique to Islam and Mormonism both explicitly acknowledge maybe celebrate the place of warfare and even violence in God’s plan.

Polygamy.

Both religions regard tobacco, caffeine and alcohol as a forbidden defilement of the flesh in any increment (serving to further set their adherents apart from European based culture).

Both religions require special garments (serving to further set their adherents apart from European based culture).