Jesus entrusted the keys of His Kingdom to Peter: “You are Peter and upon this Rock I will build my Church and the Gates of Hell shall never prevail against it. Whatever you declare bound on Earth shall be bound in Heaven and whatever you declare loosed on Earth shall be loosed in Heaven.” Accordingly, the Catholic faith teaches that the Pope and the Bishops — the successors of Peter and the Apostles — have spiritual authority. Jesus also taught: “Give to Caesar what belongs to Caesar and give to God what belongs to God.” As a result, the Christian faith has maintained the necessity for a separation of Church and State — and a separation of duties to each — long before Thomas Jefferson ever did.
Protestantism is a challenge to the spiritual authority of the Catholic Church. Once the authority principle has been challenged, there tend to be one of two general results. In the absence of a separate spiritual authority within the Church, Martin Luther believed that the State should control the Church — thus preserving a legitimate source of authority. John Calvin fiercely disagreed. He supported a more Biblical separation of Church and State. He believed that the people were covenanted to the State. This was the ideological germ out of which was born the idea of Natural Rights in addition to Natural Law.
During the Protestant Reformation, Lutheranism and Anglicanism came to dominate Protestant Europe. The mighty armies of England and Prussia fought to ensure that Martin Luther’s vision of State control of the Church dominated Protestant Europe. Puritans were repeatedly defeated and persecuted by Catholics, Anglicans, and Lutherans. After Napoleon, state control of the Church was (and mostly remains) almost universal in both Catholic and Protestant nations. When the Left swept across Europe launching a full-fledged attack on Natural Law, Anglicanism and Lutheranism slowly came under the influence of Leftist ideology. Catholicism became politically impotent in Europe.
In the United States, things were much different. Catholics, Lutherans, Anglicans, and Puritans were thrown together into an enormous melting pot. The Catholic Church in the US was until 1965 time very introspective, defensive, and self-contained. Due to its fortress mentality, it had little influence over the Protestants in the United States.
A question arises: Did Lutheranism and Anglicanism — managed by state control in their respective mother countries in Europe — exert Leftist influence on American Protestants?
Not for a long time.
They would have but the Evangelical movement swept up most Protestants into a more Calvinistic belief in personal holiness and the separation of Church and State. This occurred during the First Great Awakening from 1720 – 1750 (which helped build support for the Declaration of Independence), the Second Great Awakening from 1800 – 1840 (which helped build support for the Abolition of Slavery), and the Third Great Awakening from 1880 – 1910 (which helped build support for Prohibition and Women’s Suffrage). Each Great Awakening was followed by a Populist breakthrough in the United States. The Great Awakening sparked renewed commitment and fidelity to Natural Law and Natural Rights (except in the case of Prohibition, which was a radical overreach).
Throughout Leftist governmental control of the Church, the State had often de-emphasized Christian teachings less convenient (like certain moral teachings) and put greater emphasis on those teachings more conducive to Leftist rhetoric (like solidarity for the poor). By 1930, the Left was finally prepared to attempt to challenge Christian dogma.
Modernism had been on the upswing in Mainline Churches (the more government-controlled Churches adhering more to the principles of Martin Luther). Modernists argued that Christian dogma had to change with the times. In Europe, the times had become almost universally Leftist. Fundamentalists and Evangelicals (ideological heirs of John Calvin) fiercely disputed that any Christian teachings had to ever change.
According to universal Christian thought (until 1930), sex has always been both unitive and procreative. In order for the sexual act to have its most full, most beautiful, and most powerful meaning, it had to be within the context of a life-long commitment, fully unitive, and open to new life. Christians believed anything less cheapened the act of sex as God had intended it. Christianity has never ideologically compartmentalized sex in order to separate it from either procreation or the raising of children.
Contraception advocate, Planned Parenthood founder, and atheist Margaret Sanger attended the Lambeth Conference where Anglicans issue dogmatic statements in 1930. Over the vehement objections of most of the American Anglicans, the Lambeth Conference for the first time announced that contraception was a morally acceptable choice. In 1931, the Federal Council of Churches in Christ made a similar pronouncement.
This was the first time in the history of Protestantism that a long-held Christian doctrine was repudiated. Furthermore, a direct attack was launched on the Natural Law from within Christianity. This allowed the Left to gain its first real foothold in the US.
Throughout this era, the Catholic Church was insular and not very influential.
This was how the Left used Mainline Protestantism to promote its ideology first in Britain, then in the Anglican Church, and then in the Episcopal Church on this side of the Atlantic.
The Left has retained a firm foothold in the United States ever since.