(a) The Bill of Rights protects religious freedom by including the First Amendment, which states that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof." This means that the government cannot establish an official religion or interfere with an individual's right to practice their own religion. At the same time, the First Amendment also prohibits the government from becoming too closely connected to any particular religion, establishing a separation between the state and religion.
(b) Incorporation theory is a legal doctrine that holds that the protections guaranteed by the Bill of Rights apply to the states as well as the federal government. This means that the states must also respect the rights outlined in the Bill of Rights, and cannot infringe upon them. The incorporation theory was developed through a series of Supreme Court cases, beginning with the landmark case of Barron v. Baltimore in 1833, in which the Court held that the Bill of Rights only applied to the federal government and not the states. Over time, the Court has gradually extended the protections of the Bill of Rights to the states through the incorporation doctrine, using the Fourteenth Amendment's Due Process Clause as a legal justification. As a result, many of the rights outlined in the Bill of Rights, such as freedom of speech and religion, are now protected at both the federal and state levels