Deep down we all know that it is immoral to use coercion against people who have done no harm. When we do so it is because we are afraid and it is easier to control others than it is to control our fears. But the key to both enduring personal happiness and ending barbarism in the world at large is developing the courage to do unto others as we would have done unto to us and to face and overcome our fears instead of seeking to control other people.
It is key to enduring personal happiness because when we act in disharmony with our conscience our conscience will punish us relentlessly. We can try to silence it by lying to ourselves in various ways but any relief achieved by this means is only temporary. The shame of having caused harm to others endures and forever prevents us from experiencing deep and enduring joy.
It is key to ending barbarism because the decision to use coercion against another is the spark that lights the flame of the cycle of barbarism by which low level conflicts escalate into large-scale violence.
The key to ending it all is for each of us to make a moral commitment to resist the temptation to impose our will on other people and to encourage others in our sphere of influence to do the same.