Complex sentence: Miłosz was raised Catholic in rural Lithuania and emphasized his identity with the multi-ethnic Grand Duchy of Lithuania, a stance that led to ongoing controversies; he refused to categorically identify himself as either a Pole or a Lithuanian.
Split into simpler sentences: Miłosz was raised Catholic in rural Lithuania and emphasized his identity with the multi-ethnic Grand Duchy of Lithuania, a stance that led to ongoing controversies. He refused to categorically identify himself as either a Pole or a Lithuanian.