At the church I attended as a child, the pastor gave wonderfully entertaining sermons. Showtime's new TV movie "Common Ground" is a sermon, too, but not entertaining. It's as simple as that. One may appreciate and even applaud the movie's little messages without liking the dull and clumsy way it delivers most of them.

"Common Ground" ostensibly depicts changing attitudes toward homosexuality in a small Connecticut town over a period of about 45 years. The first act of the trilogy, "A Friend of Dorothy," written by Paula Vogel, is about a young woman who returns home in 1954 after being dishonorably discharged from the Navy for alleged lesbianism.

The second story, "M. Robert," by Terrence McNally, is set in 1974 and concerns a high school swimmer whom teammates taunt for being, or appearing to be, gay. Harvey Fierstein wrote the third story, "Andy & Amos," set in the year 2000. Things have changed enough in the town that two men can now get married in public--though not without protesters picketing the ceremony.

"Common Ground," premiering at 8 tonight, would barely be worth mentioning if not for the fact that while the first two stories are poorly written and heavy-handed, the third is so promising and enjoyable that with a rewrite or three it could probably be turned into a full-length movie all by itself. It helps that Fierstein cannily and generously includes humor in his story, doesn't take himself or the situation with aching seriousness, and again proves himself a skillful entertainer--even if a sermon can be detected in this tale, too.

Of course, the period in which Fierstein's story takes place is not as oppressive to gay people as were 1954 and 1974, when the other two stories occur. The first is the worst, and seemingly a rip-off besides. The title, "A Friend of Dorothy," also appeared in a short film by Raoul O'Connell that was part of "Boys Life," another trilogy of short films on gay experiences that's aired on cable's Sundance Channel.

The phrase is, according to both films, a kind of code term among homosexuals derived from the big gay following for the movie "The Wizard of Oz" and for Judy Garland, who of course played the heroine, Dorothy Gale. O'Connell's use of it is unimpeachable, but for Vogel to include it in the gay vocabulary of 1954 is highly suspect. For one thing, "The Wizard of Oz" was a largely forgotten movie in 1954, not being fully acknowledged as a national treasure until 1956, when CBS began airing it annually on TV (the first time in black-and-white!).

In 1954 Garland was about to make a comeback in "A Star Is Born." Was she truly a gay cult figure then? It's doubtful. The heroine of Vogel's story is also named Dorothy, so using the phrase is conveniently cute. But still sounds anachronistic.

Vogel's Dorothy, played in a dank daze by lame Brittany Murphy, is arrested during a raid at a gay bar while there with her pal Jason Priestley. Dishonorably discharged from the Navy, she arrives home in Connecticut, where her mother (Margot Kidder) is less than understanding: "I've brought you up to be better than that, and you've disgraced me!" She also refers to her daughter's "filth" and "perversion." And throws her out.

A friend comes up with good advice: Go to New York City, where you can act as wacky as you want and nobody will care. Of course, this was in those blissfully tolerant pre-Giuliani days.

The title character of the second story is a French teacher played by Steven Weber who fails to come to the aid of the harassed young swimmer played by Jonathan Taylor Thomas.

Monsieur Robert, as he has the class address him, is also gay and withholds support for the boy because he has ambitions of becoming principal of the school. Has it ever been common to search for principals within the ranks of French teachers? Mais non.

Finally comes the third story and a jolt of happy life. Andy and Amos, longtime companions who've decided to get "married," are as jittery and anxious as a heterosexual couple would be, and Fierstein has a good time making that point.

Meanwhile Ed Asner gives a robust, endearing performance as the father of one of the grooms. This character is drawn with far more credibility and finesse than the "heavies" in the other stories, most of whom are just one-dimensional drooling goons. The inevitable father-son talk may evoke memories of Archie confronting Meathead on some other issue in "All in the Family," but Asner helps keep it fresh.

Fierstein, who appears in the film as a florist, knows how to tell a story with a moral and keep the moral from becoming a thick wet blanket. It's a talent that others involved in "Common Ground" do not have in common.