I'm curious why you point out that Islam's theology doesn't hold that God is three persons with one divine nature? Are you saying that Islamic theology proves that Moslems don't worship the same God as Christians and that they are therefore destined for eternal damnation? If so, do the Jews, who also deny trinitarian theology, worship a different God from Christians, and are they therefore also destined for eternal damnation like the Moslems?
Respectfully,
The short answer is yes. The long answer (OK, not long, but longer and slightly more in depth answer) is on post 86.