Did you watch the coronation of King Charles a few weeks ago? The elaborate ceremony wedded Anglican religion with the monarchy, as has been done for centuries. The King swore to defend the Church of England and is given the power to appoint all senior clergy. He was anointed with holy oil and given Communion by the Archbishop of Canterbury. This union of state and church is exactly what the Constitution forbids and, thank God, it does!
The Founding Fathers and patriots of the United States specifically rejected the entanglement of the institutional church and the federal government, as clearly stated in the First Amendment. They were Catholics, Protestants, Jews, Deists, and Rationalists who united to create a secular state. This First Amendment was written following pleas from a liberty-loving Baptist named James Leland and others who met with James Madison, arguing for liberty of conscience and against the state being connected with a religion. Ultimately, Madison wrote much of what became the Bill of Rights for the U.S. Constitution. Dozens of laws and Supreme Court decisions have cemented this principle. Looking to Article 6 of the Constitution, where a religious test is prohibited as a qualification for public office, this strong wall of separation is further clarified. For more on this, look at the website of the Baptist Joint Committee, a non-sectarian group dedicated to religious liberty. Looking at the evidence, it is clear that the government of the United States of America is a secular nation. Period.