Please remember history.
There's more going on here than Ted Kennedy's drinking habits.
Religious organizations have a longer and more illustrious history of persecuting people for non-orthodox behavior than the United States has history at all.
The concern is not whether someone is "too Catholic", but whether someone will attempt to inflict one religion's orthodoxies upon the entire nation from a position of public power and public trust.
I leave you to contemplate that, and to remind you that Big Religion and Big Government have been synonymous for most of recorded human history. In some places, they still are. Not in the US, presently.