Top Trump administration officials will address a mass prayer meeting in the heart of Washington Sunday – an event organisers bill as reclaiming the country’s religious foundations, but critics say is a quasi-official rally for Christian nationalism.
Protestant services are also called “mass”.
In almost no Protestant demonination, except perhaps the Anglo-Catholic faction within the Church of England (called in the US the Episcopalians).
Sounds like you have never been a churchgoer in the US.
Or maybe you are thinking of evangelicals.