The previous chapter has charted the broad outlines of the path which led towards the emergence of the secularized society of States which has characterized international relations since the mid-seventeenth century. Whereas the influence of the Judaeo-Christian tradition played a dominant role in the shaping of this system, that system, once established, paid less and less heed to its religious origins. It has been seen that the ‘just war’ concept itself first grew from Christian roots but then grew away from Christianity and became a vehicle of the ius gentium. With Victoria, Gentili and Grotius, the freedom of peoples to adhere to religions other than Christianity was recognized, albeit subject to a series of caveats which demonstrate a less than perfect adherence to principles of tolerance and equality.

It has now become a commonplace to fix the date of the Treaties of Westphalia (1648) as a milestone in the evolution of the international system. Whether this be true or not, they are of particular significance in the context of religious freedom since they paralleled these doctrinal developments by recognizing the Protestant (Lutheran and Calvinist) faiths at an international level and placing the States party to them under an obligation to respect the religious beliefs of those subject to their jurisdiction.

It is Richard Zouche who is credited with having coined the phrase ‘ius inter gentes’. This marks the shift that was taking place from the inchoate concept of a society of nations in which all sovereigns derived both rights and duties under the laws of nature to the concept of a society of States in which rights and duties are owed to each other.