The God of your Books did not tell you to kill innocent people who were neither opposed to you nor in a position to hurt you. Your leaders told you to do that. Your leaders are human. They are driven by political will and lust for power over the weak. That is nothing the God of your Books and your hearts instructed you to do. You are performing an act of human will, not God. The Words of the God in your Books had never said, "Go forth and kill women and children, everyone who disagrees with you, the old, the infirm and people who are not even capable of taking up arms against you, who do not even know your cause." Your God did not tell you to do this. The leaders who ordered you are human, and ordered you to do so on human whim. The justice you seek for your fellow humans, whatever that justice may be, is human, and your violence is also human. You are not fighting a trial set by your God. You are bringing a trial set by your God upon other people. That is your folly for doing so. But the God of your Books did not say you would be rewarded for it.
If Allah were to punish men for their wrongdoing, He would not leave, on the (earth) a single living creature: but He gives them respite for a stated Term: when their Term expires, they would not be able to delay (the punishment) for a single hour, just as they would not be able to anticipate it (for a single hour).
They attribute to Allah what they hate (for themselves). And their tongues assert the falsehood that all good things are for themselves: without doubt for them is the Fire, and they will be the first to be hastened on into it! - Surah Al-Nahl 61-62