I cannot help you with regards to the Anglosphere, but I can provide what I believe to be among the first cases of Westerners frowning upon racism. An early example of racism as we would recognise it today was in Spain in the 16th Century. The Toledo Statute of 1547 made Limpieza de Sangre - purity of blood - a necessary prerequisite for anyone seeking to hold a canonry or similar high rank within the Church. In practice, this meant being able to prove that none of one's ancestors were Jews or Conversos for the past 4 generations. Though racism against Jews and strictly religious anti-Semitism can be difficult to distinguish, in this instance race was clearly the deciding factor.

J.H Elliott's Imperial Spain 1469-1716 states that the statute was "greeted with vehement protests", though regrettably he does not go into further detail. It would be helpful to know on what grounds precisely these objections were based, for instance.