Liam Purcell from Church Action on Poverty told Premier that these salaries cannot be justified by saying people work hard: "There are people who're working 20 hours a day, who're working three jobs, still not getting enough to get by.
"But there isn't some magic amount of work that those people are doing that is somehow worth millions and thousands more than ordinary people are receiving."
He was speaking after a new study found that chief executives will have been paid more than the average worker's annual salary by Tuesday afternoon.
The High Pay Centre claimed that top bosses will have made more than £27,500 in 2016 so far.
The report found that FTSE 100 executives earned the equivalent of £1,200 an hour in 2014, taking into account long hours and lack of holidays.
Liam Purcell told Premier: "It's frankly immoral for people to be receiving those type of packages when there's people in their companies who aren't even earning enough to survive."
He said that the church tries to address inequality in wider society: "Pope Francis said just a year or two ago that inequality is the root of social evil.
"That gap between rich and poor, it's very harmful to society and to our relationships with one another."
Listen to Premier's Hannah Tooley speak to Liam Purcell here: