The freedom of religion is one of the oldest and most controversial of the claims that are now recognized as forming part of the corpus of human rights. Individuals may themselves make a claim for religious freedom against their own State. The response by the State to such a claim is, ultimately, a matter of domestic policy and law. States themselves may seek to ensure that their own nationals living in other countries are free to practise their religion. Historically, this has been an aspect of the treatment of aliens but is now increasingly subsumed within the ability of States to seek to ensure that other States allow religious freedoms to all within their jurisdiction, including their own nationals. This is the area now embraced by international law under the language of ‘human rights’.

Although not couched in the language of ‘human rights’, much of the earliest writing from which international law has grown was concerned with the relationship between God and mankind. Whereas the modern focus is upon the freedom of man to act in relation to God as he (man) feels is appropriate, the original focus was upon the capacity of God to limit the range of temporal actions permitted by man. Thus while we today are concerned with the freedom of worship and the manifestation of religious beliefs, earlier writers were concerned with the limits to the power which the secular authorities could legitimately wield with regard to their subjects, or, indeed, their enemies.

Early societies identified themselves with their deity in such a way as to make the concept of freedom of religion an irrelevance.