Europe, the source of many immigrants to the American colonies, is defined by a history of interaction between the church and the state. In 1095, European noblemen responded to the pleas of the Catholic Pope Urban II and embarked on the First Crusade. The Catholic Church and European leaders maintained a strong relationship throughout the Middle Ages. Monarchs in England and France believed that their authority to lead came from God under the "Divine Right of Kings." In Spain, the Catholic monarchy started the Inquisition in the 15th century to expel Jewish and Muslim people from the state or convert them to Catholicism through torture and violence.
The Protestant Reformation in the 16th century further shaped the relationship between church and state. In Germany, Lutheranism appealed to princes and became the official religion for many German states. In 1534, King Henry VIII of England split from the Catholic Church, established the Anglican faith as the state religion of England, the Church of England as the state church and himself as the head of the church. In 1618, the Thirty Year's War resulted from growing tensions between Protestant and Catholic forces in Germany and parts of mainland Europe.
Seminal events like the Protestant Reformation and the Thirty Year's War displayed the lack of religious uniformity in Europe. Minority religious groups suffered from state sanctioned persecution and violence, and sought an escape. For some, immigrating to colonies in North America presented that opportunity. In 1630, Puritans left England to establish the Massachusetts Bay Colony and escape persecution from the Anglican Church. In 1681, William Penn founded the Pennsylvania colony to provide a safe haven for the persecuted Quakers, and the colony's policy of tolerance attracted other persecuted groups like the Moravians.
By 1776, most of the 13 colonies developed conflicting stances on the relationship between church and state. For example, Pennsylvania's 1776 constitution prohibited state interference with religious freedom, but only extended rights to those who believed "in the being of a God." Similarly, New Jersey forbid the establishment of religion, but it only protected the rights of Protestants. At the extremes, the New York constitution banned those in "the service of God" from holding elected office while the 1777 Georgia constitution required that elected officials be Protestants. Likewise, Maryland only allowed Christians to hold elected office.
At the conclusion of the American Revolution, the states favored the free exercise of religion, but it had no uniform policy on the establishment of religion. The Articles of Confederation, passed in 1781, was silent on the issue of the government endorsing a particular religion. The US Constitution, successor to the Articles of Confederation, remained silent until its Framers added the Bill of Rights to ensure ratification. The First Amendment, part of the Bill of Rights, stated "Congress shall make no law respecting an establishment of religion." Thomas Jefferson commented on the policy behind the Establishment Clause, stating that one's religion is a private matter protected by "building a wall of separation between Church & State."