And I would assert that you are either being naive or disingenuous when you said: "Killing in the name of religion generally requires men to ignore the dogma and doctrines, since love, mercy, compassion and justice are core values in most of the world’s religions."
I'm not a religious scholar, but from what exposure I have had, I would say that with the Abrahamic religions specifically, there is ample opportunity to be found within their dogma and doctrines to be unloving, unmerciful, and dispasssionate to those outside their sect defined definition of the faithful.
And of course, whether they choose to be merciful or unmerciful, it will always be justified.