What does the establishment clause in the First Amendment prohibit?

The establishment clause in the First Amendment prohibits the government from establishing a national religion, which is a crucial aspect of the principle of separation of church and state. This clause ensures that the government cannot favor one religion over another or compel citizens to practice a particular faith. By preventing the establishment of a national religion, the clause protects the freedom of individuals to worship as they choose, or not at all, thereby fostering a diverse and pluralistic society where various beliefs can coexist without governmental interference or support. This principle has been upheld by various Supreme Court rulings that interpret the establishment clause as a safeguard against religious favoritism and the entanglement of government and religious institutions.