You're right about the Catholics, Metroman, but at the time, as Andu said, Parkes and many others saw them as a real threat to society, not far behind the Chinese. If you read some of his speeches about 'the Papists', he made Pauline Hanson seem to the left of 'Watermelon' Lee Rhiannon in comparsion.
As late as the 1960s, there were numerous cases in Australia of sons or daughters being disowned by their parents for marrying across the Catholic/Protestant divide.
As a child, (late 50s, possibly very early 60s), I can recall our family being invited to a wedding "in the wrong church" and our parish priest forbidding my mother from attending the service. She ignored him, but I think we both looked up to the rafters when we walked into that church expecting the roof to come tumbling down on top of us!
The Catholic church's insistence that all children of "mixed marraiges" be brought up Catholics wasn't too far removed from the present day Muslim insistence that any non-Muslim male marrying a Muslim woman converting to Islam. (Funny how they don't insist on the same thing when the genders are reversed.)