Thus far Christianity, Judaism, and Islam agree on their conception of God. Is this enough for all three to refer to 'God' and mean the same thing? I think that it would be safe to say that all three share a similar conception that crystalizes in the word 'God,' in a way that is radically different from, say, a Hindu or Buddhist's conception of deity (or lack of such a conception). If a Hindu speaks of 'God' I can be sure he has nothing close to classical monotheism in mind. But if a Muslim or Jew speaks to me of 'God' I can be pretty sure that we share many basic conceptions.
Yet there are still massive differences between our conceptions. I believe, and the Christian faith orthodoxly recieved, says of God that yes He is One, but He is God in Trinity, and that the Second Person of the Trinity has become man. For a Jew or Muslim this is extremely problematic to say the least. But can we still share the term 'God' and imagine ourselves having some common ground in using it?
That goes not only for Muslims, but for Jews and non-Trinitarian Christians: if I speak of God to them are we talking about the same thing? I think the answer is yes and no. It cannot be an unqualified yes, for the non-Christian (yet still monotheist) conception of God is non-Trinitarian, and Trinitarianism is at the very core of the Christian faith and understanding of God. It cannot be sacrificed whatever Episcopelian bishops say. Yet I do not think that I must speak of 'god' when I am refering to Jewish, Islamic, or otherwise non-Trinitarian monotheists: there is enough common ground for us to all speak of God even though we do not mean the exact same thing, when in fact we have very serious and important divergences.
REAL Prophets climb mountains to be closer to God.
They don't crawl into a hole to listen to the hissings of a Serpent.
It's no accident that møølimbs pray with their faces to the dirt, and their arses pointed at Heaven.
This gets repeated a lot but it isn't true. The Arabic word for god is ilah, not allah. Allah is a proper name, like Jehovah or Zeus, refering to a specific individual rather than a general concept of deity.
Arab Christians use Allah in their religious language
Yes they do; they didn't before Islam gained dominance of the middle eastern regions, though (900 AD or so). Political and cultural domination of a region inevitably results in such contamination of the native population.
Thus far Christianity, Judaism, and Islam agree on their conception of God
I don't agree. Just having a few similar traits (omnipresent, omniscient, etc) doesn't mean the concept is the same, especially when there are numerous traits that are incompatible.
But can we still share the term 'God' and imagine ourselves having some common ground in using it?
Certainly; at least if you don't care what particular deity you happen to be worshipping. If we're only concerned about some vague concept of God and we really know in our rational minds that God doesn't really exist or that our concept of God isn't really accurate and it's all made up anyway, then sure; it's fine. But if God is real; if God actually exists as a person, then I think he would get as annoyed by having people worship an imposter as you or I would if someone stole our wallet and went around pretending to be either of us.
That goes not only for Muslims, but for Jews and non-Trinitarian Christians: if I speak of God to them are we talking about the same thing?
I think your answer of "yes and no" applies here fairly well. It is possible (such as Christians might assert that the Jews believe) to have an incomplete view of God, just as it is possible (as the Jews might assert or Christians might assert over other denominations) to have an erroneous view of God. But in the case of Jews and Christians it is fairly clear that at least the same entity is being discussed. In the case of Islam we're dealing with a different entity altogether.
The problem is that you simply can't ignore the real facts just because a proponent of the religion asserts that you should. The problem is that Islam claims to be an Abrahamic faith, but that Ibrahim actually worshiped this other god named Allah all the time and that the Jews and Christians got it all wrong. Islam makes certain claims that can't possibly be true. Ignoring the religious claims and looking at secular history, we know the Kaaba was a temple for a pantheon of gods (among whom was Allah) and that before Mohammed came along there was no philosophical nor historical connection to the Jewish or Christian faith.
In short, we know Islam is based on lies. Perhaps Judaism and Christianity are also false religions as some atheists might claim, but in their case at least they are internally self-consistent. There is no obvious historical evidence that proves Christianity to be false, but the same cannot be said for Islam. If as a greek I were to destroy the temples of all the other deities of the greek pantheon and assert that Zeus almighty is the only true god, that doesn't mean that Zeus then becomes the same entity as Jehovah or Allah or Dave, and it certainly doesn't mean that I should translate "Dave" as "God" just to placate someone who might think Dave is so great that he should be worshipped as the creator deity.