Recently some US public Christians have claimed that Jehovah and Allah are the same person (God). Al Mohler has refuted this on his blog. A similar view at Reformation21.
There is more to say, however.
In brief; Mohler refers to the linear view of history. Islam has a view of history as arbitrary process; Christianity does not.
God is love in the Bible. In Islam God is despotic and calls for the death of the 'unbeliever' not his redemption.
[The acts against those who would oppose Israel in the promised land
are not relevant, as the point is not unbelief per se, but untrammeled
evil: consider the references to Moloch and Sodom].
Philosphically Islam's monotonic deity necessitates the world being framed in a rigid unity that is internally referent and intolerant of diversity; indeed, for which diversity is abhorrent. Thus Islam. The triune God within himself shows unity and fellowship in diversity; whence love.
The only way to certainty of salvation in Islam is martyrdom. In Christ it is faith!