President Reagan is unequaled among politicians in his ability to sound magnificent and downright silly on the same theme. Both the magnificence and the silliness were amply displayed on his visit here, thanks largely to the inability of key advisers to square extravagant rhetoric with realistic policies.

Reagan had excellent reasons for visiting Indonesia. He canceled a state visit here in 1983 as a byproduct of his decision not to go to the Philippines after the murder of Benigno Aquino. Indonesia is the world's most populous Moslem country and a strategic barrier to the spread of communism and Islamic fundamentalism.

The United States, the only major western power to support Indonesia in its struggle for liberation four decades ago, is grateful that neither the Libyan People's Bureaus nor the Palestine Liberation Organization are allowed to function here. At a time of falling oil prices, Indonesia is a Third World success story with a growing economy. Reagan respects Indonesian President Suharto for leading his nation from a starvation economy to self-sufficiency in rice production.

After 20 years of Suharto's authoritarian rule, however, Indonesia is neither a mirror image of the United States nor a model of democracy, and Reagan did no favor to anyone in suggesting that it might be.

In a gushy speech before he left Washington, the president made a strong case for the power of freedom, but it was marred by the excessive claim that "winds of freedom" are blowing in Asia and throughout the world. "The developing world has been told that it is necessary to give up freedom in order to achieve progress; nothing could be further from the truth," Reagan said. "Freedom and economic advance go hand in hand."

By the time Reagan had reached Guam, the winds of freedom were approaching typhoon velocity. Speaking to U.S. service personnel, Reagan said there is a "necessary connection between freedom and economic growth." He also made the inaccurate assertion that the foreign ministers he would meet in Indonesia have "in large part embraced human liberty, both political and economic."

A few hours after this flight of fancy, two Australian broadcast correspondents who had said nothing critical of Indonesia were refused admittance in Bali on the White House press plane because an Australian newspaper had dared to criticize corruption in Indonesian government circles two weeks earlier. A New York Times correspondent was thrown out of the country, in part because she had arranged interviews for her editor, who subsequently criticized the Suharto regime. Newspapers printing articles referring to Indonesian government corruption, one of them written by me, were barred from the country or crudely censored.

None of this suggests that Reagan should have avoided Indonesia, the world's fifth most populous nation and one too frequently neglected by the United States. It does suggest that Reagan, who speaks more eloquently for human liberty than any president since John F. Kennedy, should get his facts straight before he opens his mouth or boards Air Force One.

Reagan finds this very difficult to do, if the facts get in the way of his thesis. The facts are that political freedom is a rarity on this globe, despite the contrary assertion of the so-called Reagan doctrine. Rather than acknowledge this unfortunate reality, Reagan discovers that the People's Republic of China is "so-called communist China" after he visits there, and he sees democracy flourishing in Indonesia where none exists.

Small wonder that the theme for this trip, as cynically suggested on the White House press plane, was "windbag of freedom." Reagan is an impressive representative of his country, and he is right in valuing Indonesia and its Southeast Asian neighbors. But by making unsupportable claims for the spread of human liberty where little exists, he undermines rather than advances the cause of freedom.

Reaganism of the Week: Asked last Thursday if the Soviets had adequately informed the United States about the nuclear power-plant disaster, the president replied: "Well, they're usually a little closemouthed about these things, and this is no exception."