and even if you ignored the legal context (what is opinion vs what is mitzvot)<quoted text>
"The following do not have any portion in the world to come, their souls are cut off forever:...koferim ba-Torah.
Koferim ba-Torah are those who maintain that God has replaced or nullified the mitzvot, such as the Muslims and Christians" (Mishneh Torah, hilchot Teshuvah)
but i guess Maimonides too had a "very narrow interpretation" of "Frijole's religion"
the fact is most Jews today do not waste anytime worrying or even thinking that nonJews are unworthy of going to heaven or not.
So yes, your view would be a very narrow interpretation.