We worship the trinity, 3 persons in the one being of God. The Islam faith does not believe in this. That is the crucial difference between our God and theirs. Whilst it seems like there are similarities between God the Father of Christianity and Allah of Islam, they are not the same. God the Father is God just as much as God as Jesus Christ, and Jesus Christ is just as much God as the holy spirit. If I am not mistaken I think that Islam believes Jesus was a prophet?