Freedom of religion is a principle that supports the freedom of an individual or community, in public or private, to manifest religion or belief in teaching, practice, worship, and observance; the concept is generally recognized also to include the freedom to change religion or not to follow any religion.
Freedom of religion is considered by many people and nations to be a fundamental human right.
Among the most contentious areas of religious freedom is the right of an individual to change or abandon his or her own religion (apostasy), and the right to evangelize individuals seeking to convince others to make such a change.
In international law the freedom of religion and belief is protected by the International Covenant on Civil and Political Rights (ICCPR).
Different countries have different statutes with regard to religious Freedom. The may or may not of have signed the UN Declaration on Religious Freedom.
Religious freedom is a foreign policy of the United States, who advocate on the behalf of the individuals viewed as persecuted in foreign countries on the account of religion. The United States, through its constitution and various international agreements, supposedly has an obligation to support religious freedom around the world by skirmishing religious intolerance in countries that put sanctions on the religious rights of the people.
You can read more on Freedom of Religion
You can read more on the US Freedom of Religion Act of 1998