Most Christians probably do not understand FOR SURE that Islam (Allah/Muslim) is completely different. Muslims are familiar with Christian scripture for a few reasons,...
1) they believe that Jesus is the messenger of God the Creator.
2) they want to be able to disguise themselves as having something to do with Christianity so as to decieve younger Christians (they have been trained well in this).
3) they profess to be sons of Abraham (Genesis 21).
(I say "for sure" because it's difficult to get the straight story from a Muslim, in MY experience).
Their belief is that their prophet Mohammed (400 years ago) prophesied, taught and formed their belief. It is a 400 year old belief (laugh). There have been Muslims all throughout history (100 years war, etc.), but the modern generations only believe in a 400 year history (at least that's all they will willingly reveal, lest they be obligated to actually make sense out of what they're taught).
People of any culture can be wondeful people, but some have just never been able to overcome their ethnocentricity. What's more, the eastern cultures have a mistrust/resentment of the western cultures (can't blame them there). Their religion is a very closed one because they know that it can't withstand exposure (therefore they reveal as little as possible), but they wouldn't want outsiders mixing with them on an equal basis anyway.
I was apologizing in case you thought I never gave complete recognition to the sincerity of your devotion. You of course, don't have the intention of allowing anything to become an issue between yourself and The Lord (He understands that and the feeling is mutual), but others could easily misunderstand you calling The Lord Allah and be misled because they don't yet have a close personal relationship as you do.
If it is true that the Arab Christians call God Allah, maybe the word just means "Creator".