Without war, there would likely be a lot less freedom. We would all still be under the rule of warlords and kings. As the adage goes "Freedom is not Free". In most cases it is something you must fight for. The U.S. would not exist today (Revolutionary War). Not all wars are bad in totality (nor are they all good).
As for atomic weapons, the only time they were ever used in war, was to stop one (WWII). The estimates of dead for a full invasion of mainland Japan was about a million people. It was terrible to use them, but the alternative may have been far worse (totally debatable).
I don't think your argument is very strong. For one, we DO live under the rule of warlords and kings. Even if they don't call themselves warlords and kings.
Not only that, but all war in the past is in the past. It happened. We can't change it.
The events that shaped our history are important, and many wars did have honor and justness to them.
But I don't think we need you to go advocating for more war. War is killing people, and that sort of advocacy is violent and unnecessary. We have a lot of people who believe in the power of war. A lot. More than enough. I think we should try our hardest to speak out against war, knowing full well plenty of people want it to happen. War will happen. But there shouldn't be glory and honor in it. It is a grim, horrible thing, and I don't think we need to say "sometimes war is ok". I think both of us would grab a gun if it meant defending out home. I would, at least. I'd fight back against an invading army for sure. But that's not what we face. The modern wars we've been having are corrupt, and that's what I'm truly speaking out against.
We need to seek peace, both within out, and outside us, if we want the clarity to form allies with our former enemies and friendships with our current allies. We need to see the good in all people, even our enemies, and our enemies need to see the good in us.
War is a means, not an end. We want peace, justice, freedom, privacy, etc. If we can attain them without war, then yes. However, war is sometimes the path that gets society there.
You say you are willing to fight and if necessary kill for things you believe in. The same principle can apply with respect to war. If your nation is invaded, is grabbing a gun to defend your home, family, friends, and rights to choose your government justified? Then you have chosen war.
It is convenient and easy to say war is 'bad'. It may even feel good. But it is an oversimplification of the complex world. We should be brave enough to see society in a pragmatic way, with realism, to find the right balance and guardrails of what acts we are willing to pursue. I believe there are very few absolutes in life, 'war is bad' is not among them. I am not advocating war in general, just resolve in my position, that war is a necessary option some of the time.
PLEASE NOTE: I have all the respect in the world for your opinion. I am not trying to change it. I am simply giving my opinion and the supporting reasons why I hold my position. I give you full credit for having your viewpoint and greatly respect the fact you are willing to discuss it publicly.