The one "less" tool is imaginary, and inevitably there will be another tool.
You see, the "tool" is a symptom of mankind's disease of causing wars.
But if you were to find a "cure", you don't just cure the symptoms, you cure the disease.
That disease, is human emotions, and human nature itself.
Can you remove human nature?
There will be a new debate going on if people are focusing on that instead of religion.
What's funny is, instead of blaming human nature's superstitions and imaginations, they blame ON the superstitions and imaginations.
Whether religion is man-made or not, it has been used, modified, for misinterpretations.
To blame on religion for being making humanity stupid is to exempt the infinite possibilities that humanity can be stupid in many ways, i.e. human nature.
Why blame religion for making people stupid, ALLOWING people to believe that the removal of religion will also remove their stupidity as well?
This is how it'll happen:
Remove religion, and mankind's will find a NEW religion:
It is called utilitarianism. Will mankind be so stupid to use this a new tool like how do they do it in religion? Oh yes. It is called, the evolutionary imperative, the best excuse for the superior to have TOTAL power over the inferior, justifying MURDER and KILLING as a NATURAL RULE for the survival of the fittest, esepcially the rule of "good and evil" are beset among those who in the majority who THINK it's good because it serves their purpose, and to those who studied psychology, the emotion of FEAR, will finally have NEW excuses to think that "necessary evils" are completely justifiable by utilitarianian rule. And will that start another war? You bet.
And those who like NUMBERS, and think religion caused the most deaths in wars, Y'ALL OBVIOUSLY HAVE NOT HEARD OF GENGHIS KHAN'S GENOCIDES, which is completely non-religious.
Remember it is also human psyche that make us decide not to cause war as well. Human phsyce is not all negative.
The new religion will not work because we as a civilization learn from our past and its time for us to move on as a better species. The new religion is as simple as to embrace new ideas and leave the old and obsolete. But many will stay in the old premise of religion, trapped in time and fear. Which is their choice, which is also human pshyce to be able to choose.
I never state religion as the BIGGEST KILLER OF ALL. Religion IS one of the reason, but not all the time. If u wanna compare Genghis Khan and the Crusades, Conquistadores, The Inquisition, the Witch Hunt and the 911, all involve killing. It is what motivates them to do it matters here. U cant remove human psyche. But we all have a choice.