Secretary of State George P. Shultz, previewing the arguments President Reagan will make in Sunday's second debate with Walter F. Mondale, said yesterday that Reagan's leadership in foreign policy has inspired "a new patriotism, a new pride in our country, a new faith in its capacity to do good."

"The United States is a very different country than it was five or 10 years ago, and our allies and our adversaries both know it," Shultz said, in the most unabashedly partisan speech by any secretary of state in recent memory.

" . . . Today we face the future stronger and more secure. We are better able to deter challenges, or to meet them. Future presidents, facing a potential crisis anywhere in world, will thank their lucky stars that Ronald Reagan has given them the tools to defend American interests," he said.

It was an uncharacteristic performance for Shultz, who usually takes a lofty, above-the-battle tone in his public utterances and who has played no open part in the presidential campaign.

Yesterday, he used a speech to the Los Angeles World Affairs Council to sketch the outlines of the foreign policy accomplishments Reagan will try to emphasize when he debates the Democratic presidential nominee in Kansas City.

Shultz described the Soviet Union as on the defensive everywhere before "a more vigorous and self-confident American posture," and added:

"Restoring the people's confidence in American leadership has been perhaps the president's most important goal in foreign policy.

"Yes, we have rebuilt our military strength; yes, we have put our economy back on the path of sustained growth without inflation; yes, we have conducted a vigorous diplomacy to help solve international problems.

"But these achievements reflect and reinforce something even more fundamental -- our people's renewed self-confidence about their country's role and future in the world."

Shultz even sought to portray as a success the administration's controversial policies in Lebanon.In Sunday's debate, Mondale is expected to criticize Reagan sharply for not preventing the three terrorist bomb attacks in Lebanon that took a heavy toll of American lives.

Mondale also is likely to recall that terrorist pressures forced Reagan to withdraw U.S. Marines from Beirut in February and that the administration was unable to prevent the Lebanese government from renouncing its U.S.-sponsored peace accord with Israel.

"In Lebanon," Shultz said, "we negotiated the removal of 11,000 Palestinian terrorists from Beirut in 1982, and in 1983 we negotiated an agreement that would have ensured the security of Israel's northern border, Israeli withdrawal from Lebanon and a restoration of Lebanon's sovereignty. We are proud of that achievement, and whatever setbacks may come, we will not let up our efforts."

In a speech in Los Angeles on Thursday, Shultz signaled a more flexible and conciliatory approach toward the Soviet Union on arms control and other issues that divide East and West.

Yesterday the secretary of state repeated U.S. willingness to negotiate, but also said he expects the Soviets to respond favorably because Reagan's policies have left them no choice other than "an adjustment to the new reality" of American resurgence.

"Their political warfare against NATO deployment of intermediate-range nuclear forces in Europe was a failure," he said. "Their attack on the Korean airliner brought universal condemnation. Their Afghanistan invasion has met with tough, unyielding resistance. Poland has raised ominous questions about the viability of their Eastern Europe empire. Their attempt to repair relations with China has gone flat. In southern Africa and in the Caribbean basin, their clients are on the defensive. At home, they face deep economic difficulties and leadership uncertainties."

"Our adversaries are burdened . . . . The United States is strong and once again comfortable with its role of leadership," Shultz concluded. "I can assure you that a major goal of President Reagan in a second term will be to summon again the spirit of bipartisan cooperation. It will be a time for a reaffirmation of unity . . . [to] reforge a national consensus on foreign policy that will sustain America's leadership in the world over the long-term future."