Complex sentence: Some of the treatises which have come down to us were written after he had become separated from the Catholic Church; yet, whatever verdict may be passed upon this great man, his works remain among the most valuable of Christian antiquity.
Split into simpler sentences: Some of the treatises that come down to us were written after he separated from the Catholic Church. Yet, whatever verdict may be passed on him, his works remain among the most valuable of Christian antiquity.