Hundreds of people have taken part in a protest outside a Ballymena church which received millions of pounds in donations from Wrightbus.
One of the pastors at Green Pastures Church is Jeff Wright, who also controlled the Wright group.
It received more than £15m from the firm in recent years, most of which was donated while the group was profitable.
About 1,200 people lost their jobs when Wrightbus was placed into administration.
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The protesters began arriving outside the church at 09:00 BST, and an estimated 500 people had gathered within two hours, many carrying placards.
There were some police officers both inside and outside the church, but the protests were peaceful.
Wrightbus founder, Sir William Wright, stopped to speak to some of the protesters on his way into the church and was applauded by many of them.
Stephen McMaster said he had clapped because “nobody in the whole of Ballymena or this workforce runs down William Wright for this chaos”.
Another protester said he was there because the workers had “nowhere to go, nobody to see” and they wanted answers.
Fiona Knowles, Sir William’s granddaughter, joined protesters outside the church.
She said she had lost her job at the company more than a year ago and it broke her heart.
“I have lost everything in my life,” she said. “I am having to rebuild my life again so I know how these guys feel.
“I just hope we can find a buyer because it is a good company with a good product and these guys deserve better.”
Later, inside the church, Jeff Wright received a standing ovation during his sermon.
Mr Wright was tearful as he defended his recent public silence.
On Sunday night, the church posted online what he had said.
“My heart for the company and its people means more to me than the vicious comments and the intimidation that my family have received in the last week,” he said.
“But I have learned from dad that there’s a time to speak and a time to be silent.”
He said talks to try to save the workforce were ongoing and he did not want to say anything that would jeopardise the negotiations.
During the service, anyone affected by the collapse was asked to stand while the rest of the congregation prayed for them.
Mr Wright said he was working hard to ensure there was future employment for the workers.
The Green Pastures charity received £15m in donations from Wrightbus over six years, and some workers have expressed concern the donations weakened the business.
The Wright family, who founded Wrightbus in 1946, say the collapse of the business was due to a big fall in demand for buses in the UK market.
The group, which had been suffering from financial problems and was up for sale, went into administration on Wednesday.
The Wrightbus factory is owned by another firm Whirlwind Property Two, separate from the manufacturing company.
Whirlwind Property Two is controlled by Jeff Wright, the main shareholder in Wrightbus.
The family have denied they acted unreasonably during attempts to sell the business.