What are Paul Johnson and Howard Zinn's theses regarding religion in America, and what do they say to support their theses?

Paul Johnson traces American history as having established a religious divide between the Northern and Southern colonies. In A History of the American People, Johnson notes that the Northern colonies of New England were religious and idealistic, with an "overpowering inward compulsion to live a godly life." In the South, with its multitude of indentured white labourers and black slaves, religion existed "as a function of gentility and class." Johnson credits religious ideals to having "sounded the death-knell of American slavery."
Johnson also discusses how America's Christian foundations, which had been taken from England, eroded over time. He associates this shifting Christian ideology with Calvinists's pursuit of religious freedom and the gradual rejection of Puritanism. As Johnson approaches the modern age in his text, he observes that the historic role of religion in America has been downplayed since the 1960s. He asserts that America increasingly viewed religion as an opposition of progress, a belief that had also taken hold at the same time in Europe.
Howard Zinn's text, A People's History of the United States, conveys historical America as having exploited its people and slaves through systems that favored the elite. In particular, he discusses the psychological and physical disempowerment of slaves, that which was supported by religion. In order to maintain the idea of black inferiority and respect for the masters, slaves were made to understand their supposed divine subordination. Religion was thus used as a means of control. Zinn includes a passage taken from the Cotton Plantation Record and Account Book, which many planters consulted:

You will find that an hour devoted every Sabbath morning to their moral and religious instruction would prove a great aid to you in bringing about a better state of things amongst Negroes.

Before and after slavery was abolished, Zinn asserts that "religion was imbedded into every aspect and institution of American life." Religious ideologies were taught in church, school, and within the family, particularly "to keep women in their place, even as that place became more and more unsettled." Religion dominated the idea of sexual purity as a special virtue possessed by women; according to Zinn, "it was assumed that men, as a matter of biological nature, would sin, but woman must not surrender." Women were thus responsible for maintaining religion within their families.
Zinn asserts that in the mid-19th century, "party politics and religion now substituting for class conflict," opposition developed between Irish Catholics and Protestants. Zinn puts forth arguments that are similar to Johnson's in terms of religion since the 1960s. As part of a general movement against rigid historical ways of living, the idea of religion in conflict with societal progress was established, as religion dictated many elements of life.