Death in War.

"Dead lungs command it, you pour your life down the rifle's spiral" Commanders (dead men walking) give commands for soldiers to go forth into battle - essentially the soldiers putting their life into the hands of their rifles, and at the mercy of the enemies', throwing or 'pouring' their life away.

"Clerics fog will recede right before your eyes" Many wars, current and past, are based off religious spins to drive a sense of that culture or peoples morality into the war for support. But once as a soldier out on the field, dying, you realize everything they said was for nothing. All the reasons they gave you fall away and you are left with the grim reality of war.

"So long to this wretched form" Death of the soldier, he no longer has to be a glorified murderer of men, women and children. He no longer has to commit the atrocities of war.

"Long before you were born, you were always to be a dagger floating, straight to their heart" Likely a reference to the children born during wartime, who are exposed only to the propaganda of war. The soldier was born into a culture of fighting and recruitment - and had no choice but to be born into the role of a soldier - and to be sent into war against the enemy to strike at their "heart"

"Listen, now, we won't tell anyone.
But you're gonna tell the world.
This whole life ain't been any fun
Now your viscera unfurls."

This verse is very clear that life as a soldier is grim and is a struggle of death, suffering, and a lack of black and white morality. The soldier has suffered through war, and now finally he has been mortally wounded, "viscera unfurls".

"As you rise, rise from your burning fiat,Go, go get my suitcase, would you?" Freed by death, the soldier no longer has to obey the futile commands to his death. The suitcase reference demonstrates Mercer's view that war is petty and soldiers are sent to their deaths for pathetic causes.

"You're not invisible, now.
You just don't exist.
Your mother must be so proud.
You sublimate yourself, granting us a wish."

This verse, post death of the soldier, explains he is no longer alive - ceased to exist. Their 'mother must be so proud' - is is noble to have a son die at war for their country.

"Primitive mural on the wall,
to fortify your grim resolve.
And made the glitz of a shopping mall
another grain of indigent salt to the sea."

War memorials are placed to remember the soldier(s) so that we can show respect for how our government, and the governments of other countries killed them. The 'glitz' is how they are glorified and romanticized as out sons and daughters who died for us, but as another grain of poor salt in a sea of countless who have died for the same reasons - only to see more wars over and over again.

The fundamental theme of the song is the futility of war - and the little value placed on human life for what are trivial and petty interests thrust upon the common man by corporates, politics and (religious) officials.