The International Convention on the Elimination of All Forms of Racial Discrimination was adopted and opened for signature and ratification by the United Nations General Assembly in resolution 2106 (XX) of 21 December 1965. It entered into force on 4 January 1969. 

Article 5 

In compliance with the fundamental obligations laid down in articel 2 of this Convention, States Parties undertake to prohibit and to eliminate racial discrimination in all its forms and to guarantee the rights of everyone, without distinction as to race, colour, or national or ethnic origin, to equality before the law, notably in the enjoyment of the folowing rights: 
(...) 
(d.vii) The right to freedom of thought, conscience and religion.