This paper assumes the author’s conceptual analysis of rights as complexes of Hohfeldian positions that confer dominion on the right-holder in face of one or more second parties and his theory of moral reasons as essentially social dual-aspect practical reasons, both explained in previously published books. It analyses the international human right to have or adopt a religion or belief of one’s choice and the international human right to manifest one’s religion or belief in worship, observance, practice and teaching as liberties of individual human beings protected by duties of non-interference and immunities from extinction holding against State Parties. It then identifies their moral grounds, the most important moral justifications for recognizing and maintaining these religious human rights in international law. It suggests that these are analogous moral religious human rights and some of the morally proper purposes of international law, including the promotion of international peace. It explains how the problematic human rights to change one’s religion or belief and to proselytize one’s religion or belief can be derived from the more basic human rights to have or adopt a religion or belief and to manifest one’s religion or belief respectively. It examines the reasons that many deny these rights and argues that, correctly interpreted, they are morally justified. Finally it reexamines the question as to whether the human rights to have or adopt a religion or belief and to manifest one’s religion or belief do more to threaten or to promote peace. It argues that although these human rights threaten peace to a limited extent, on balance they would, if universally respected, protect and enhance both internal and international peace even more. It concludes that there are two important relations between these religious human rights and peace. Both would be conducive to peace were they universally respected. And this fact is one of the moral grounds of these human rights in international law.