If forgers and malefactors are put to death by the secular power there is much more reason for excommunicating and even putting to death one convicted of heresy.
When you're young you're always wondering when you're actually going to feel like a grownup. And I think you probably fear it in a sense too. There's a danger to feeling like an adult... like this whimsical kid in you is going to die or something. And then all of a sudden one day you kind of feel like an adult and it's really nice.