The problem with all of these not a real Muslim arguments is that they are essentially based on differing interpretations of Islam's worldview, scripture, theology. Differing versions of Islam -- but obviously sourced in the same worldview, scripture and basic theology so they are all obviously under Islam's umbrella. Its ridiculous to try and divorce Islam from the ideology from which these terrorists operate.
And the truly ironic thing is that they are doing the same to you (moderate Muslims). They are saying that YOU are the ones who are not following the TRUE faith.
It sounds utterly ridiculous to the ears of non-Muslims.
Instead of denying that these people are Muslims, practicing a form of Islam -- why don't you present arguments about why their interpretation is incorrect and yours is correct? Why don't you concentrate on showing us the loving and merciful G-d which exists in Islam? Why don't you just acknowledge the problematic verses and demonstrate how you understand them? It really would go much farther towards peace to do this.