JC: As an adult.
JM: As a child!
JC: Really?! But do you think in the film, they were successful?
JM: No, they weren't, but they had more power as children. The magic, the power they have as the seven of them when they come together, aided by the turtle — key player in the book, not so much in the film — troubles Pennywise so much.
Pennywise actually says this at some point. He says, "How are you going to beat me? You can only beat me by your collective imagination and your unified belief, and your fears are what form me. When you were kids, you used to believe in magic."
JC: But you also had more fears.
JM: Well, you did, but you also used to believe in the power of magic. Now you believe in the fucking IRS, so how are you going to beat me?
JC: We disagree on this one. I'm adult, you're child.