The greatest concentrations of roman catholics today are found in europe and

The Catholic Church has had its own supremacy since centuries. Catholism dominated in countries which were colonized by Spanish and Portugal mainly.

Roman Catholism is dominant is various parts of Latin America. This is a result of Spanish and Portugese colonies in Latin America and the Roman Catholic missions that accompanied the colonization. Catholism survived even after the end of colonization.

Catholism is also dominant in European countries. Central and other countries in Europe have Roman Catholism as one of the major religions being followed.