The Spirit of Vatican II doesn't scare us anymore; with the advent of the internet, sunlight and exposure has helped to beat back the damage it's dished out since the 60's.
Of course, such a costume would elicit different reactions depending on where you donned it; in Lincoln, Nebraska, you'd probably be given rocks by good Catholics, a la Charlie Brown. But in places like Los Angeles, you'd be welcomed as an old friend.
Me? I'll be going out on Halloween as a mild-mannered father of 4, escorting the boys on their yearly Candy Shakedown. I'll be the one with gray hair...