Taking a brief foray down a sideroad here, I'd like to make a comment in connection with your opening statement- When a Christian murders people or even when Christians promote hatred against groups like gays, many other Christians will say “But he is not a true Christian”.

Why is it that, by and large, it is rare to hear such disavowals pronounced by "christians" when a member of another faith acts openly and often violently against the recognized principles of their own religion? Why do the same people, who easily distance themselves from transgressors of their faith by labeling the transgressors as "not true christians" then proceed to hold transgressors of other faiths as valid representatives of those faiths? Where, I ask, is the "Christianity" in that sort of behaviour? Where is their forgiveness, their belief in the goodness of humanity? One answer to these questions is "hypocrisy", and another is "ignorance", and both of these essential "christian" qualities appear to be paramount in the practice of Christianity and every other religion.