To me, this is the lead singer (Matt) talking about flaws that he has, and that because of these flaws, he can't be trusted and will inevitably let you down.
This part:
"How could you do this to all your believers?
How could you do this to all your friends?
You know this is the end."
seems to be his loved ones talking to him, asking how he could let them down. That's why they used the gang vocals there. It's not him talking to himself in the third person, it's all of the other people talking to him. Then it comes back in with just him singing about himself again with the "I know this is the end".
To me, this is the lead singer (Matt) talking about flaws that he has, and that because of these flaws, he can't be trusted and will inevitably let you down. This part: "How could you do this to all your believers? How could you do this to all your friends? You know this is the end." seems to be his loved ones talking to him, asking how he could let them down. That's why they used the gang vocals there. It's not him talking to himself in the third person, it's all of the other people talking to him. Then it comes back in with just him singing about himself again with the "I know this is the end".