Ok, let me break this down for you guys. Nagato used to be very similar to Naruto. He was very kind of heart, forgiving, brave, and loving. This inspired Jiraiya to the point where he wrote the Gutsy Ninja about him, obviously not knowing Naruto would actually be prophetically born. Unfortunately for Nagato, he lost faith in the inherent goodness of humanity, instead choosing only to see our dark side.
Before Nagato became the evil bastard that we know and love today, he truly believed in his heart that love and dedication to peace on an individual level would eventually save the world. Jiraiya realized the profoundness of that thought and chose to believe in it himself, thus dedicating his entire life to it.
Since Naruto believed in Jiraiya wholeheartedly much like Jiraiya believed in Nagato, he also believes in the power of peace, love, persistence and forgiveness to change the hearts and minds of others, thus bringing real change to the (ninja) world.
What I think a lot of you guys are failing to understand is that Nagato was the original philosopher behind Jiraiya and Naruto's ideologies.
When Naruto spoke to Nagato about the Gutsy Ninja, it reminded him that he too was once a "Gutsy Ninja" too, and that there was nothing forcing him to continue along his evil path.
I think the fact that Naruto essentially forgave Nagato for everything he did (I'm sure he thinks Hinata is dead), forced Nagato to reconsider the philosophy that he originally created and Jiraiya taught to Naruto. After all, it's gotta be hard to spare the life of the guy who destroyed your village, but Naruto manned up and showed to Nagato that
"the day will truly come when people change"
I know a lot of you guys thought this chapter sucked, but I thought it was pretty deep.