By the time Charles Calvert became governor, the population of the province had gradually shifted, due to Puritan immigration, becoming, in time, an overwhelmingly Protestant British colony.
Political power, however, tended to remain concentrated in the hands of the largely Roman Catholic elite.
In spite of this demographic shift away from Catholicism, Calvert attempted to preserve Maryland's Catholic identity.

From 1669–1689, of 27 men who sat on the Governor's Council, just eight were Protestant.
Most councillors were Catholics, and many were related by blood or marriage to the Calverts, enjoying political patronage and often lucrative offices such as commands in the militia or sinecures in the Land Office.
In response, Maryland Protestants quickly organized into anti-Catholic militias, known as "associators".
By the time Charles Calvert became governor, the population of the province had gradually shifted, due to Puritan immigration, becoming, in time, an overwhelmingly Protestant British colony. Political power, however, tended to remain concentrated in the hands of the largely Roman Catholic elite. In spite of this demographic shift away from Catholicism, Calvert attempted to preserve Maryland's Catholic identity.
From 1669–1689, of 27 men who sat on the Governor's Council, just eight were Protestant. Most councillors were Catholics, and many were related by blood or marriage to the Calverts, enjoying political patronage and often lucrative offices such as commands in the militia or sinecures in the Land Office. In response, Maryland Protestants quickly organized into anti-Catholic militias, known as "associators".
Protestant Revolution (Maryland)