Conversion to Christianity is the religious conversion of a previously non-Christian person that brings about changes in what sociologists refer to as the convert's "root reality" including their social behaviors, thinking and ethics. The sociology of religion indicates religious conversion was an important factor in the emergence of civilization and the making of the modern world. Conversion is the most studied aspect of religion by psychologists of religion, but there is still very little actual data available.
Christianity is growing rapidly in the global South and East, primarily through conversion. Different methods of conversion have been practiced historically. There is evidence of coercion by secular leaders in the Early and Late Middle Ages, though coercion as a method has never been approved or even supported by any majority of Christian theologians.