Honestly, on a global level and a war level, I think it will be achieved in like 100-300 years once religion and communism have both died out....if they die out.
Sociologists predict that Atheism will become the leading belief system (or in this case, lack-of-belief system) by 2034, but the date of all religion dying out hasn't been estimated yet. There will probably never be a day when all individuals stop believing, but there will come a day most major religious organisations are dissolved, and religions will become local, rather than global.
On an individual/community level, no. There will always be murderers, mass murderers and serial killers. And that's not peaceful.
All world religion teaches essentially the same thing - peace. Religion is not the problem. It actually offers solution to the problem. It's the people that twist and pervert the teachings of their religion to suit their personal agendas that is the problem not religion itself. Unless there is only one common belief that can be agreed upon by everyone, there will always be something for people to argue or fight with each other.
No, 'cause we're too different and we can never agree. Plus, I think we secretly like conflict… maybe if we can agree to a non-violent conflict style that can resolve our issues without having to shoot, stab, or lace anybody…
There will always be disagreements/conflicts between countries, as it is a natural part of human nature, but I think it's definitely possible to live in a world without war.
This. Countries have to realise that war nowadays achieves nothing. It's not 1356.