What is the meaning behind This is War by 30 Seconds to Mars?

Answer 1

Most likely its about fighting for what you believe in weather you want to or not. At the end of the song he implies that he believes in nothing, so he's probably fighting the people who want him to share their beliefs. He's fighting on the spur of the moment when anything is possible, he just wants to be left alone.

Answer 2

A Warning to the people,

The Good and the Evil

This Is War

To the Soldier, The Civillian, The Martyr, The Victim

This is War

Its the moment of truth and the moment to lie

The moment to live and the moment to die

The moment to fight, the moment to fight, to fight, to fight, to fight

To the right To the left we will fight to the death

To the Edge of the Earth, It's a Brave New World from the last to the first

To the right, To the left, We will fight to the death

To the Edge of the Earth, it's a Brave New World it's a Brave New World it's a Brave New World

A warning to the prophet, the liar, the honest

This is War

To the leader, the pariah, the victim, the messiah

This is war

Its the moment of truth and the moment to lie

And the moment to live and the moment to die

The moment to fight, the moment to fight, to fight, to fight, to fight

To the right, To the left, we will fight to the death

To the Edge of the Earth, It's a Brave New World from the last to the first

To the right, To the left, We will fight to the death

To the Edge of the Earth it's a Brave New World, it's a Brave New World, It's A Brave New World

I do believe in the light, raise your hands up to the sky

The fight is done, the war is won, lift your hands toward the sun

toward the sun, toward the sun, the war is won

fight fight fight fight fight (choir)

To the right, To the left, we will fight to the death

To the Edge of the Earth, It's a Brave New World from the last to the first

To the right, To the left, We will fight to the death

To the Edge of the Earth it's a Brave New World it's a Brave New World It's A Brave New World

A Brave New World

The war is won,

the war is won,

a brave new world

I believe in nothing not the end and not the start

I believe in nothing not the earth and not the stars

I believe in nothing not the day or not the dark

I believe in nothing not but the beating of our hearts

I believe in nothing not 100 suns until we part

I believe in nothing not not in sin and not in God

I believe in nothing not not in peace and not in war

I believe in nothing not but the truth in who we are