Vexed issues for the Catholic Church such as women priests and homosexuality are not matters that are subject to the whim of the pope, a Catholic leader says.

Father Brian Lucas, the general secretary of the Australian Bishops Conference, says it was possible a new pope could be chosen from South America, Asia or Africa but the church's attitudes to these issues were fundamental doctrinal issues.

"I don't think we can take those sorts of issues and think these are matters that are simply changeable at the whim of the next pope," Fr Lucas told ABC TV on Tuesday.

"We're looking at trying to discern the truth."

The 85-year-old Pope Benedict XVI announced his decision to step down during a meeting of Vatican cardinals on Monday morning (local time), saying age prevented him from carrying out his duties.

Answering a question on whether Pope Benedict did enough to progress the church, Fr Lucas said progress was not necessarily positive.

"Progress is always one of the those words that we have to discern with some care. Sometimes you can progress to somewhere you ought not go," Fr Lucas said.

"Modernity has to be discerned not so much by what is modern or new but what is good and true and beautiful."

On the matter of Pope Benedict's response to child sex abuse by church members, Fr Lucas said the leader of the Catholic Church had been decisive.

"When he was in charge of the congregation for the doctrine of the faith - that's the department that has the power to bring priests to justice within the church system - he was very decisive in the steps he took there," Fr Lucas said.

"Whether or not he took personal responsibility and whether or not his statements were sufficient will be a matter about which people will have very different views."

On who would be elected the next pope, Fr Lucas said the college of cardinals would be likely to make a decision on individual personalities rather than geography or race.

"They'll look for the person who they see has the qualities to lead the church into the next few years," he said.

"We'll have to wait and see how the holy spirit moves the minds of the cardinals as they talk amongst themselves."