Quarterback Joe Theismann, who crossed the picket lines the last time the National Football League Players Association went on strike, said today he would go along with whatever a majority of his teammates decides this time, even if they vote to strike.

"Whatever a majority of this team does, I'll do," said Theismann, who is not an advocate of the union's demand for a percentage of the owners' gross revenue. "That's because unity is the most important thing to this team. I think it's important the Washington Redskins stay together no matter what happens.

"We can't have 40 guys go out and five stay in, for example. Nor can 40 stay in and five go out. We can't have a division within our ranks, because I'm convinced somehow we will play a football season this year and it would be disasterous to have everyone pulling every whichway.

"I may not think percentage of the gross is the best way to go. I happen to like more liberal free agency rules. But I have had my chance to voice my opinion and I will continue to voice it. Then if it comes down to a team vote, and I hope it never does, the majority will rule. That's the only way it can be."

Until now, Theismann had been noncommittal about what he would do if the Redskins decided to strike. But it has become apparent that most of the veterans here support the union.

In 1974, when the NFLPA went on strike, Theismann was starting his first season with the Redskins after playing in the Canadian Football League. He chose to cross the picket lines, he said, because he had yet to make the team and felt he should be in camp. But he admits his decision was resented strongly by Redskin veterans and led to bitter feelings between him and many of the older players on George Allen's last Washington teams.

But now, entering his fourth year as full-time starter, Theismann is one of the leaders on a team that has only 12 players left from the Allen era.

Led by Mark Murphy, the team's player representative, a growing nucleus of Redskins is becoming increasingly disturbed by the state of the negotiations with the league. Even Theismann, who says he is neither prounion nor antileague, sounded like a union man in his denounciation of the NFL's current tactics.

"It's shame, what's going on," he said. "The NFLPA wants to negotiate . . . it is trying to arrange a negotiating spot (near a training site) that would allow players on the negotiating committee to participate.

"But Mr. (Jack) Donlan (chief league negotiator) says it's New York or nowhere." (Actually, Donlan has said that the NFL Management Council will meet in New York or Washington.)

"That shows me they don't want to really settle this issue. Who cares where they meet, as long as they start talking? They want to push this as far as they can and as long as they can to see if the union can hold up under pressure.

"If they don't like our proposal, make one of their own and not that awful thing they brought to the table recently. Give us something on free agency, on second medical opinions, on access to our own medical records. Let's have some movement."

Players interviewed here almost uniformly reflected tackle George Starke's view: "I think the union is getting stronger every day because of the lack of negotiations. Even the so-so union players see what management is doing. I think the owners made a mistake, waiting like this. And they'll be wrong until owners come to the table and start negotiating.

"Coming to camp has increased communication among the players and made us more unified. If there is a strike, this team will go out. I think 95 percent of the players in the league will go out."

Safety Mike Nelms: "I wasn't going to talk about the negotiations once I got to camp but I changed my mind. We have to get the word out to the public that we aren't the bad guys here, that the owners are stonewalling us. There is a lot of strong feeling on this team about how we are being treated."

The labor problem, which makes this camp different from any since the mid-1970s, is discussed here frequently, but it is not the focus of dinner conversations every night, nor is it hindering preseason preparation.

"I can't say that it affects your play during practice, but it is in the back of your mind," guard Russ Grimm said. "You can't afford not to get ready for the regular season, although when you think about Philadelphia (opening game), you wonder if there will be a season."

Running back Rickey Claitt: "I can't control what's happening so I'm just going about my business trying to make the team. That's what I'm concentrating on right now."

Although the Redskins are one of the more miltant union teams in the league, Grimm also concedes that not every player shares his feelings about the NFLPA.

"I'd say that one-third of the players are very strong for the union. There is a middle third that will support the union, no matter what, but their interest isn't as high. And there is another third that is so confused by being in camp and trying to make the team that they haven't had time for anything else. They are just trying to survive."