President Reagan looked to the future with a vision from the past last night, declaring that "the conservative movement in 20th century America held fast through hard and difficult years to its vision of the truth."

Speaking before the friendliest of audiences, the Conservative Political Action Conference, which Reagan has addressed in six of the eight years of its existence, the president praised his loyal supporters for the backing they gave him in lean years.

And he also harkened back to his own frankly conservative view, which first brought him to public attention as a spokesman for Barry M. Goldwater in 1964.

"Who can forget that July night in San Francisco when Barry Goldwater told us that we must set the tides running again in the cause of freedom 'until our cause has won the day, inspired the world and shown the way to a tomorrow worthy of all our yesteryears'?" Reagan asked rhetorically, "Had there not been a Barry Goldwater willing to make that lonely walk, we would not be talking of a celebration tonight."

Veterans of the ill-fated Goldwater campaign had much to cheer about in Reagan's speech. The more than 1,000 people present gave the president an extraordinary reception -- they gave him a two-minute standing ovation before he started to speak, then interrupted him with applause and cheers 16 times.

Reagan was clearly trying to convert the converted. As if he wanted to drive the point home, he arrived early for a reception and stayed for almost two hours through a dinner of rice and veal.

Seated near the president at the head table were his chief of staff, James A. Baker III; Education Secretary Terrel H. Bell, and Housing and Urban Development Secretary Samuel R. Pierce Jr., all of whom have come under harsh criticism from conservatives.

Longtime conservative favorites such as Martin Anderson, Reagan's chief domestic adviser, and Richard V. Allen, his national security affairs adviser, were in the audience.

After paying tribute to a number of conservative leaders such as Russell Kirk, Henry Hazlitt, James Burnham, Frank Meyer and Ludwig von Mises, and conservative publications such as National Review and Human Events, Reagan said:

"Because ours is a consistent philosophy of government, we can be very clear: we do not have a separate social agenda, a separate economic agenda and a separate foreign agenda. We have one agenda.

"Just as surely as we seek to put our financial house in order and rebuild our nation's defenses, so too we seek to protect the unborn, to end the manipulation of schoolchildren by utopian planners and permit the acknowledgement of a Supreme Being in our classrooms just as we allow such acknowledgements in other public institutions."

While Reagan has touched on all these themes before, it was the first unabashedly ideological speech he has given as president.

He took advantage of the sensibilities of his audience to reassert his fundamental view of communism as the essential enemy.

". . . The Marxist vision of man without God must eventually be seen as an empty and a false faith -- the second oldest in the world -- first proclaimed in the garden of Eden with whispered words of temptation: 'Ye shall be as gods.'

"The crisis of the western world, Whittaker Chambers reminded us, exists to the degree in which it is indifferent to God. 'The Western world does not know it,' he said about our struggle, 'but it already possesses the answer to this problem -- but only provided that its faith in God and the freedom He enjoins is as great as communism's faith in man."

Reagan did not merely celebrate the past; he promised to stand "shoulder to shoulder" with his fellow conservatives in the battle against abortion and for school prayer. His remarks on such favorite issues of the New Right drew some of the loudest applause of the night.

Amid his remembrances of conservative causes, the president softly injected one note of political realism, saying that it is not going to be easy to carry out the entire conservative agenda.

"Now obviously we are not going to be able to accomplish all this at once," Reagan said. "The American people are patient. I think they realize that the wrongs done over several decades cannot be corrected instantly."

But the president left no doubt about his long-term agenda.

"Our goals complement each other -- we are not cutting the budget simply for the sake of sounder fiscal management," he said. "This is only a first step toward returning power to the states and communities, only a first step toward reordering the relationship between citizen and government. We can make government again responsive to the people but only by cutting its size and scope and thereby ensuring that its legitimate functions are performed efficiently and justly."