... and the bias then was political as much as religious. As recently as 1960 there was a great deal of worry, as to whether Kennedy would have allegiance to the United States or to the Vatican. You hear it even today in the illegal immigration battle.
The early colonial exception was the Palatinate of Maryland, established by a convert to Catholicism with the permission of a king that most falsely assume to have been “Protestant.” Church of England and Anglican Communion types never did cotton much to being called “Protestant” and still don’t.
Maryland was indeed established as a Catholic Palitinate.
The remaining Catholics in England had some place to flee from persecution.
“However, during the protenstant expansion laws were written to strip Catholics of rights to hold office and own property.
Even in the supposedly tolerant Maryland, the tables had turned against Catholics by the 1700s. By this time the penal code against Catholics included test oaths administered to keep Catholics out of office, legislation that barred Catholics from entering certain professions (such as Law), and measures had been enacted to make them incapable of inheriting or purchasing land. By 1718 the ballot had been denied to Catholics in Maryland, following the example of the other colonies, and parents could even be fined for sending children abroad to be educated as Catholics.”
http://www.traditioninaction.org/History/B_001_Colonies.html