Hola Luis:
From a Muslim point of view, Judaism, Christianity and Islam teach the same faith:
Belief in the One and Only Creator and Sustainer of the universe
The faith conveyed by God through His prophets is the same (Monotheism), and the basic foundation of the Divine Law is the same, what evolved were details of the Law.
Hola, Cordoba. Gracias for your input.
I have a bit of trouble understanding what you mean, however. I assume that you are telling me that for a Muslim the main religious choice, and in some respects the one that is really all-important, is that of believing in Abraham's God (or perhaps simply choosing Monotheism? I don't think you are quite claiming that, say, Zoroastrism, the ancient egyptian cult of Aton or a strictly monotheistic cult of Brahma are the same as Islam, however).
That is fine, leaving aside for a moment how exactly Muslims feel and deal with the existence of people that will never be monotheists (or theists, for that matter). There is nothing wrong with being monotheist.
But what does being the same faith due to monotheism actually mean, in practical terms? Shias and Sunnis, Catholics and Anglicans, Orthodox Judaists and Humanistic Judaists, to say nothing of such weighty divisions based on the recognition of Jesus and of the Quran, are usually understood to be significant divergences and for all practical purposes distinct faiths.
Maybe I'm overstating the importance of those splits, but if so then I'm hardly alone. Fact is, except as a statement of recognition for the basic importance of accepting the One True God, not even Muslims usually treat Judaism and Christianism as being essentially the same as their own faith. I'd dare to guess that Sunnis don't often think of Shia Islam as being the same as Islam, even.
I will go so far as to say that belief in God, or even of some specific conception of God such as Abraham's, does not really say much about what the person actually has faith on. God, perhaps counter-intuitively, is not a particularly meaningful concept in a religious sense. It actually has more influence for political matters, since it appeals to the core instincs of Being In the Right when conflicts arise.