First Baseman
Retired athlete
No.
http://www.catholic.com/magazine/articles/what-no-salvation-outside-the-church-means
How can you be condemned for lacking knowledge you were ignorant of? A faithful Muslim, for instance, is not convicted of the truth of Catholicism. So why would their ignorance of it damn them? Damnation, like Salvation, is a wilful path you follow. It's based on choices you consciously make. A Muslim is serving God as best they know how, same as others of other religions. They are seeking and searching for God. They haven't rejected Him.To be damned, you must willfully reject God, despite knowing the truth. If you know the Church is the One True Church but you leave or refuse to enter her in the first place, then you are greatly imperiling yourself.
There is also a belief that the Archangel St. Michael appears to all of us at the time of our death to give us one last chance to repent. If we do, we go to Purgatory and formally accept Christ then. (Interestingly, Islam also has a tradition where people are tested in their graves by Angels for a period of time.)
That's not my place to say. I could very well end up in hell and so could you. It's between them and God. I hope we all are counted as worthy of Beatific Vision, however. That's my hope. I hope even Satan can be reconciled to God.
Muslims do believe in Christ, by the way. They believe He is the Messiah, was born of a virgin and will return. They just don't generally believe in the crucifixion or that He is the Son of God/God the Son. But we actually have far more in common with Muslims, theologically, than we do with modern Jews.
I disagree with most of what you posted. Failure to believe that Jesus died for our sin on the cross is indeed damning. Why do you think the Nicene creed is so important? Why do you think the Gospel is to be preached to all nations?
Muslims believe Jesus was just a prophet. I stop there because there is no good reason to learn more about what they believe because they're wrong.
Muslims believe that we are infidels. Why do you think Christianity isn't allowed in many of their countries? Why do you think the Bible has been banned in many of their countries? To be found with a Bible can get you jailed or put to death. Sound tolerant or brotherly to you?
Why do you assume that they are ignorant of the Gospel? Mohammed certainly wasn't ignorant of it but he taught another "gospel." Paul warned against such teachings in Galations. Don't be deceived.
On the original subject, why don't you post what the RCC catechism says about marriage and polygamy for your friend?
Would the pope agree to marry a man to more than one woman? Would any Catholic priest? Ask yourself why not. If your son wanted to do it would you give him your blessing?