The visiting relic of Saint Francis Xavier will be on display in Catholic churches in the Illawarra.
The detached arm of a centuries-old saint will tour the Illawarra in a perspex viewing box as part of an exercise in cementing Catholic faith.
St Francis Xavier's right forearm - the one he used to bless and baptise converts in the early 1550s when working as a missionary - was detached from his body and taken as a religious relic in 1614.
In a rare outing, it was brought from Rome to Sydney on Sunday by Bishop Peter Comensoli and will make more than 100 stops around Australia as part of a pilgrimage marking the Year of Grace.
On Sunday, the relic will arrive at Wollongong's St Francis Xavier Cathedral, where Bishop of Wollongong Peter Ingham will say mass at 5pm.
Bishop Ingham conceded "there will be some people who are puzzled" by the dismembered arm.
"When we look at the mortal remains of saints, they're basically just human bones - but they are the bones of people who were touched by the living power of God," he said.
"That sheds a light on a lot of the dark aspects of life and reveals God's presence."
The relic arrived in Australia encased in perspex and has since been fitted inside a timber display reliquary weighing more than 50 kilograms.
Stringent rules governed how the relic was handled, said Warwick Hansen, manager of Hansen & Cole Funerals, the company appointed to safeguard and transport the relic while it is in Wollongong.
It is accompanied by a Jesuit priest, Father Richard Shortall, at all times, and must be transported horizontally but made to stand upright for display as it enters a church.
"It's as a priest would normally bless - with their hand upright," Mr Hansen said. There are also guidelines about what priests should be wearing when they receive the relic, and where viewers should be positioned.
The relic is in the Wollongong diocese from Sunday to Tuesday, including at Wollongong on Sunday from 4pm to 7pm; Berrima on Monday from 8am to 10.30am and Port Kembla on Monday from 12.30pm to 3pm.
See www.sydneycatholic.org for the full itinerary.