The First Amendment protects religious freedom through two clauses: the Establishment Clause prevents government from establishing religion, while the Free Exercise Clause protects religious practice.
The Establishment Clause prohibits government actions that favor one religion over others or religion over non-religion. This has led to bans on school-sponsored prayer, government displays of religious symbols, and direct government funding for religious activities. The Supreme Court uses the Lemon test to determine whether government actions violate this clause: they must have secular purpose, neither advance nor inhibit religion, and avoid excessive government entanglement with religion.
The Free Exercise Clause protects religious beliefs and practices from government interference. However, this protection is not absolute. The government can regulate religious practices that conflict with neutral laws of general applicability, as in Employment Division v. Smith (1990), which upheld denying unemployment benefits to Native American Church members who used peyote.
These clauses reflect the Founders' experience with religious persecution in Europe and desire to prevent religious conflict in America. They aim to protect both religious freedom and government secularism, ensuring government neither favors nor opposes religion.
Religious freedom cases continue to generate controversy, involving issues like prayer in public schools, religious symbols on government property, religious exemptions from general laws, and government funding for religious activities.