Roll over, Barney. Here comes a tomato named Bob.

A bunch of goofy, singing animated vegetables are heading to the top of the toddler retail world. Their videos, called "VeggieTales," are often in the top 10 on VideoScan Inc.'s best-seller lists, and their songs have hit No. 1 on Billboard's children's-audio chart.Now you can also buy such Veg-gie-Tale product spinoffs as hair barrettes and kitchen clocks. The vegetables seem as uncomplicated as most other animated characters, except for one thing: They preach a Christian mes-sage.

Nathan Smith, a three-year-old in Dallas, is obsessed by VeggieTales, according to his mother, Paula Herman Smith. One of his favorites: "Where is God When I'm Scared?" in which an asparagus tip named Junior lies in bed afraid of the Frankencelery monster until two friendly vegetables appear and comfort him with a song, "God Is Bigger Than the Boogie Man." "He'll sing the song and dance while they're dancing," says his mother, who goes to church regularly but first heard about the videos at a party.

Religious video for children used to be a low-tech genre, exemplified by "Davey and Goliath," the Sunday-morning show of 30 years ago, which told Bible stories with primitive clay figures. But with religious content becoming more acceptable on television, all this is changing. PBS has put "Adventures From the Book of Virtues," animated Bible stories and fables for kids narrated by luminaries such as George Segal and Michael York, in a Sunday-morning slot. "Legends," another new children's video series available in stores, consists of animated Bible stories introduced by Charlton Heston.

VeggieTales is the Barney of this group. Technologically, it lags behind the more sophisticated cartoons, but its simple characters, bright colors and catchy tunes sweeten the Christian message. While conceding VeggieTales' current popularity, Virginia Robertson, West Coast editor of the trade magazine KidScreen, wonders if the characters have the star charisma that made Barney so successful.

Mainstream retailers are banking on it. Since spring, Junior Asparagus has been sharing shelf space in Kmart and Kroger stores with videos of Barney the dinosaur and Disney characters. Last month, two VeggieTales videos made their debut on Wal-Mart shelves.

The veggies are the brainchildren of two 32-year-olds, Phil Vischer and Mike Nawrocki, who met at St. Paul Bible College in 1984. Both were puppeteers, expert in silly voices, and after college worked at computer-animation companies with dreams of making their own cartoons. Because computer animation was still technologically primitive, their characters had to be simple. "We asked ourselves, `What kind of character could we develop that has no arms, no legs, no hair and no clothes,' " says Vischer. The answer, of course, was a cucumber.

The result? Big Idea Productions Inc., a closely held Chicago company that invented VeggieTales and shipped nearly two million videos last year, up from 50,000 in 1994, for total sales of more than $20 million. Of that, Big Idea reaped royalties of about $4.5 million. It has licensing agreements with a dozen companies, up from three two years ago. And now Vischer is working on a feature-length vegetable movie.

Some retailers aren't interested in carrying the religious vegetables, in part because of their strong evangelical message. Zany Brainy, of Wynnewood, Pa., a chain of 57 stores specializing in educational toys, doesn't carry VeggieTales videos. "We only can carry so many tapes," says a spokesman.

"Obviously, it's extremely Christian in nature," says Sue Bristol, vice president of marketing for Lyrick Studios, Dallas, the creator of Barney that also distributes VeggieTales to the secular market. "You definitely do take your chances there."

The main VeggieTales characters are an odd couple: a squat, serious tomato named Bob and a lanky, scatterbrained cucumber named Larry. They "walk," more or less, by hopping. Together, they narrate and enact skits - aided by a chorus of squash, berries, asparagus and peas - with a moral at the end.

The 10th title in the series, which came out in July, is "Madame Blueberry," about a plump round fruit who thinks she would be happier if she had more stuff - that is, until she sees little children thanking God for small blessings, such as a piece of pie. The moral: "If you don't want to be a grumpy berry, you should be thankful for what you have." Each episode ends with the phrase, "Remember kids, God made you special, and he loves you very much."

Among evangelical Christian young adults, the veggies have a cult following, analogous to the adult audience of "South Park."