Brief Summary
The Set-Up
Marshall's point: things are really bad, you guys. If the United States doesn't help Europe's economy, we're going to be staring down the barrel of another world war with so many communists.
The Text
Turns out that war is bad for places. (We know; we're surprised too.)
Even before the actual outbreak of fighting, the Nazis had pretty much destroyed their economy by shifting everything over to manufacturing tools of war. Since we just fought those guys, and don't want to again, they're not allowed to do that. So what's next?
It gets even worse once you factor in the whole idea that manufacturing and transportation hubs were military targets. So in winning the war, the Allies pretty much crippled Europe's economy. Go team.
The trick, according to Marshall, is to help bring the economy back and restore the spirit of people who've been bombed. A lot. The answer: cold, hard cash. The U.S. was pretty untouched by the war, so there's cash to spare. And, if we help Europe recover, it does good things for the world and keeps them from going over to the communists.
TL;DR
The U.S. doesn't want a communist Europe, so we should give them money.