What amendment is being violated if Christianity is made as the official religion for the Us.?

If Christianity were made the official religion of the United States, it would violate the First Amendment of the Constitution, which prohibits the establishment of any religion by the government. This is known as the Establishment Clause, which ensures the separation of church and state, protecting individuals' rights to practice any religion or none at all. Such a move would undermine the religious freedoms guaranteed to all citizens.