Complex sentence: Roman Catholicism has traditionally been Belgium's majority religion, with approximately 75% of the Belgians declaring themselves to be Catholics; however, by 2004 Sunday church attendance was only about 4 to 8% (9% for Flanders only).
Split into simpler sentences: Roman Catholicism has traditionally been Belgium's majority religion with approximately 75% of the Belgians declaring themselves to be Catholics. However, by 2004, nationwide Sunday church attendance was only about 4 to 8% (9% for Flanders only).