The phrase "a long sermon" is correct and usable in written English.
It can be used to describe a sermon that is lengthy in duration, often in a religious context.
Example: "The pastor delivered a long sermon that lasted over an hour, covering various aspects of faith and morality."
Alternatives: "an extended sermon" or "a lengthy sermon".
But what I resent in contemporary criticism is this taking a work of attempted, supposed art, as a text for a long sermon on something rather different.
One evening, he said, listening to a long sermon about "how we're all evil, lying people, and our hearts are deceitful, I was getting uncomfortable and got up to leave," he said.
Instead, the walls are full of women and children, paintings including Grecian nymphs, serene Victorian ladies arranging flowers on a sunny window seat, a little girl painted by John Everett Millais yawning through a long sermon, and two Victorian children, a match girl and a crossing sweeper, shivering in the snow as they look yearningly at a pantomime poster.
I don't want y'all to leave here thinking, "That was a hell of a long sermon!
John also includes a long sermon by Jesus, preparing his disciples (now without Judas) for his departure.
"I'm inspired by what you are doing," Reverend William Barber II, head of the North Carolina NAACP, told the workers at the beginning of a long sermon.
Another time I had been attending a pretty long sermon and the service was being held in a hotel the local community rented space in while it's mosque was being constructed.
Then he left his art dealing job, tried teaching, walked across Kent, decided to become an urban missionary and preached a long introspective sermon to baffled suburbanites.
An earnest, inert musical about the unlikely friendship forged between a white woman and an escaped slave in the South in the 1840's, it's a long, dreary sermon in song.
"Sotheby's disappointing auction felt like a long, rambling sermon, the kind where everyone is fidgeting in their seats, hankering to leave.
We eventually take it to Crissy Point and we dig a grave there, and I gave him this long sermon about how precious and fragile life is, and how Rocky, during his short life, taught us some lessons from the way it was curious, from the way it was warm.
