Five million Australians, one-quarter of the population, call themselves Catholic. At the core of their belief is the Mass, the ritual in which Christ becomes present to the faithful. Only a male unmarried priest can say Mass. The trouble is the Roman Catholic Church is running out of priests and soon won't have enough to conduct Sunday Masses. Though in some places there's been a slight increase in numbers studying for the priesthood, there are still too few to replace ageing and retiring priests. Priests are being brought in from overseas, and some former Anglican priests are filling parish vacancies. But these strategies may present more problems than solutions. Some Anglican-turned-Catholic priests are already married. So, if marriage is no impediment for them, why the prohibition on married Catholic priests? Many Catholics, including priests and some bishops, think it's time to abandon mandatory celibacy and to admit married men and women to the priesthood.