Rep. Jack Brooks (D-Tex.), the crusty arch-enemy of the federal government's general revenue-sharing program. saw that he had a tough audience yesterday.

There they sat -- 1,000 county officials devoutly dedicated to the beneficence of the program that is sending states, counties, cities, towns, townships, boroughs, Indian tribes and Alaskan native villages some $6.8 billion this year in string-free funds.

Speaking to such a group as the National Association of Counties, said Brooks, warming to the task. is "always a pleasure... It brings out the missionary spirit in me. I look out and see all those souls needing to be saved from the false doctrine of revenue sharing, and I welcome the opportunity to try to bring you into the light of reason -- and fiscal responsibility."

Like a minister trying to win the heart of a backslider, Brooks, the powerful chairman of the House Government Operations Committee, tried the friendly approach first.

"I have great regard for county commissioners," he began. "Together we've spent an awful lot of federal money."

Then he tried the empathetic approach.

"I can understand your dedication to such a program [as revenue sharing]. It is a great treat for a bpulic official to enjoy the pleasures of spending without the pain of raising the money. I don't blame you for enjoying it.

"I'd dedicate those parks and the street work and that pothole work. I'd pay a couple of cops extra money, a couple of nurses, a couple of firemen. I'd buy a new something-or-other.

"I'd smile at the people, buy a new set of keys to the city. get my picture in the paper and tell them, 'We're just trying to do a good job for the floks here down home.'"

Some of the county officials, who obviously didn't like the message, were smiling in spite of themselves.

Brooks, the good ol' boy from Beaumont, Tex., was still playing the local official dispensing the revenue-sharing largesse. He said with sarcasm, "Don't say one damn word about where they money's coming from. Just tell 'em, I'm trying to help you all.'"

Now the NACO audience was laughing, and Brooks. came to the point of his sermonette about a program that started in 1972 and, unless Congress renews it, will end Sept. 30, 1980:

"The truth of the matter is, it's a fraud." he intoned. And, seeing the smiles drop, he added, "But it's fun. I don't blame you. It's fun.

"But I'll tell you -- that fun is running out. The federal borrowing power has reached its limit.... The national debt is expected to hit $900 billion by the end of 1980. Just the payment of interest on the current debt is costing over $55 billion a year. The American people are demanding that we reduce federal spending."

Brooks concluded with something approaching a prayer, an exhortation to work together to find ways to help communities "that need help" -- ways that do not mean "simply sending them more money....

"I hope you will put your considerable talents to that task and not use them to lobby Congress for programs that will only push us farther down the road toward centralized government and fiscal disaster."

He got a standing ovation. The NACO members were smiling, laughing, applauding.

Then, a few hours later they realized what hit them. A statement was drafted and the press was called.

Charlotte Williams, NACO president and a commissioner of Genesee County (Flint), Mich., said county officials will "strongly resist" any move in Congress to cut or eliminate revenue sharing.

"Inflation has hit local governments so hard that many have been forced to use revenue-sharing dollars just to maintain existing services," she said. "If revenue sharing were eliminated, county officials would either have to raise property taxes, a move citizens would surely oppse, or curtail many services."

Williams chided Brooks for saying that aid to state and local governments is leading the country toward centralixed government and, on the other hand, for opposing revenue sharing because Congress cannot control how it is spent.

"If Rep. Brooks were really concerned about maintaining our decentralized form of government," she argued, "he would support revenue sharing because it's the one federal program allowing states and localities to make their own decisions on spending priorities."

Brooks, informed of her reaction, said he expected it. He added, "It's hardly likely that the people who are spending all that free money would want to start raising it themselves."