After further investigation, it turned out that the parishioners were simply unnerved by the presence of men between the ages of 18 and 35.
"We've never seen that before."
California parish finds out "suspicious" strangers were just Marines, not skinheads.
They actually sicced the cops on them. Niiiiice.
Probably one of those parishes that prides itself on its hospitality and inclusiveness.
"See--we put it in the mission statement!"
[Thanks to Dom for the link.]
[Update: Commenter Therese correctly notes that there are various versions of this story floating about, so it may be hard to draw a conclusion. Here's the Marine Corps Times version.]