Complex sentence: Continence was required of all Christian priests by ecclesiastical law until the great schism, and is still required of Catholic priests today; many Eastern Catholic Churches do not require celibacy of their priests.
Split into simpler sentences: Continence was required of all Christian priests by ecclesiastical law until the great schism, and is still required of Catholic priests today. It should be noted, however, that many Eastern Catholic Churches do not require celibacy of their priests.