I often wonder this.
Muslims believe that they worship the God of Abraham, the God spoken of in the Torah.
We know that as Christians, we worship the God of the bible.
Obviously the islamic faith is wrong, as they do not accept that Jesus is God, and are not saved. But are they worshiping the same God we are? Just in a distorted, incorrect and futile manner? Surely not.
I think that islam is an invention of satan, who has a keen interest in seeing it spread. The question is, is the 'God' that muslims claim to worship really satan?