The fire broke out in St. Mark's Episcopal Church on Main Street just after 5 a.m.
Firefighters from South Orange, Orange, East Orange, Maplewood and Millburn joined West Orange crews to tackle the massive blaze that took just minutes to start.
"The fire progressed very fast. It was an old church, heavy old timber in the roof (is) dry and old," said Deputy Chief Albert Souza, of the West Orange Fire Department. "There were decorations and drapery that added to the fire."
No injuries were immediately reported.
Investigators have not determined exactly where the fire started, but Souza said the fire alarms in the basement sounded. It may take several days to discover the cause.
The Essex County Prosecutor's Office arson unit is investigating. The International Federation of Chaplains, a Pentecostal congregation that owns the church, is consulting with engineers to see if what's left of the church can be saved.
It took three hours to get the fire under control.
The church dates back to 1827 and is an "outstanding example of Gothic Revival architecture," according to Preservation New Jersey. A historical landmark and an icon to locals, it was listed as one of the 10 most endangered historic sites in New Jersey.
"You know, the first thing you see when you get off 280 and you come to West Orange, is the church," said Josefa Altenburd, of West Orange. "It's one of those things that you don't believe until you see it."
West Orange resident Joseph Fagan said the church is filled with artifacts. "A former pastor's body is buried in the basement under the altar," he said.
The congregation had celebrated New Year's Eve there just four hours earlier; the celebration ended around 12:30 a.m. The minister said they did not use open flames during the service.
"We are Pentecostal, we don't use candles. No cooking - we brought food in," said chaplain Douglas Hernandez.
The congregation is looking for a temporary location to use.