Therein lies the rub. Islam has the stated intention of making every nation subservient to Allah. Moreover Islam puts the onus of carrying out that intent by means of jihad, squarely on the shoulders of men. The Muslims who do not engage in jihad are not living according to the Koran.
Christianity also does not assimilate, true. I am a Christian; I have no intention of giving up my beliefs. However nor do I intend on blowing up, stabbing, or shooting anyone who does not believe the same way I do.
Islam attempts to have men, who are (very) fallible do the sorting of who lives and who dies. Whereas Christianity leaves that sorting to God at the end of each man's life. Someone may not believe what I do - I will be happy to list why I believe the way I do, but at the end of the day, if you choose not to believe, that is your choice. And, when we die, we will see who was right and who was not.
Syrian immigrants...I'm sorry, but islam has no place in this country.