Last year about 300 people celebrated Pentecost with prayers, readings and live music at the Katoomba Christian Convention Centre.
This year the festival will be going online, due to coronavirus restrictions.
Organised by the Upper Mountains Ministers Association, which comprises about 14 churches, a special service will be held online at pentecost.org.au at 10am on May 31.
It will incorporate talks, readings, music and prayers from Anglican, Presbyterian, Baptist, Brethren, Australian Christian churches, Salvation Army and Churches of Christ denominations.
Pentecost, meaning "fiftieth'" in Greek, is traditionally held 50 days after Easter and celebrates the Biblical account of the first public Christian sermon and mass conversion after the resurrection of Jesus, followed by the beginning of a rapid expansion of Christianity that would eventually envelop the whole Roman empire.
"COVID-19 may have halted in-person public gatherings but the religious faithful have adapted like other community groups and many of our local churches are live-streaming services every Sunday," said Jon Guyer, senior minister at Wentworth Falls Anglican Church.
"We are blessed to live in this modern age of technology where online gatherings are possible."
He said services wouldn't be resuming in person at his church until stage three of the lifting of the lockdown, as they had a congregation of more than 50.
"We are going cautiously as there are elderly people who are quite vulnerable in the community," Reverend Guyer said.
"We will have drastically re-arranged seating for social distancing."
Even when churches can resume mass gatherings, Rev Guyer expected the livestreaming of services would continue, as they were reaching people who wouldn't normally attend church.
"The main obvious change has been family members who don't come to church. In the lounge room with the TV on, a lot of people felt comfortable sitting down with family members and being part of it [the service] as well," he said.
"People are seeking something in uncertain times."
Throughout the coronavirus pandemic, churches in the Blue Mountains have been livestreaming their services, holding small group Zoom meetings, and appealing to the younger generation with activities on YouTube.