Back home in Commentary magazine, Norman Podhoretz has written a mighty essay, descriptively titled “World War IV: How It Started, What It Means, and Why We Have to Win.” Mr. Podhoretz is careful in his use of language, so that when he writes of World War IV, he isn’t just using a racy metaphor. We are at war, nothing less – with radical Islamic individuals and aggregations.

We are contending with them most forthrightly in Afghanistan and Iraq, but they fester everywhere in the Islamic world, and we have, Mr. Podhoretz warns, no alternative but to persevere in the war. Wage it we must, but there is always the possibility of losing it. If we do, Commentary magazine will have a lot to say about it all, if it still exists.

Mr. Podhoretz gives us, in this long and ambitious essay, the history of the world wars we have engaged in. He doesn’t linger for very long on World War II, since its causes were, finally, as plain as the dawn light over Pearl Harbor. He does linger over the near-immediate conversion to the cause of war of the isolationist right after Dec. 7, 1941.

His focus moves then to the next great political consolidation, which came with the defeat of the capitulationist Henry Wallace movement in 1948 and the consolidation in support of the Truman Doctrine. That was World War III, which ended four decades later with the implosion of the Soviet system beginning in 1989. There had been weaknesses and there had been faltering, even during the stewardship of Ronald Reagan, he reminds us. But we made it, and waited happily around a few years for the beginning of World War IV, which was ignited on September 11, 2001.

Mr. Podhoretz examines trenchantly and with concern the subsequent movement of the dissidents. At first, the national unity was galvanizing. Doubts about our raw military prowess were speedily dismissed with the stunning victories in Afghanistan and Iraq, giving us the conquest of Baghdad and the dissolution of Saddam Hussein’s army at (in military terms) minimal cost.

But our undertaking, as outlined by President Bush in his September 20, 2001, speech to a joint session of Congress and elucidated in following months in three major speeches, including the State of the Union address, confronted more than the orthodox and relatively simple military challenge. Wars have a more contracted shelf life in the public patience than was so in years gone by. Nobody expected that the war against Adolf Hitler would quickly be over, and there was no lesion of public support for it. Mr. Podhoretz reminds us that even the Vietnam War met with overwhelming approval for three years. But this time the twitchiness began less than a year or so after our offensive launch in Iraq. The critics began not merely to carp, but to question the legitimacy of our aims – and, even, the motives of the president.

The opposition broadened its base rapidly. “What we saw developing,” Mr. Podhoretz writes, “was a broader coalition than the antiwar movement spawned by Vietnam had managed.” It was seconded “by all the Democratic candidates in the presidential primaries, except for Joseph Lieberman.” Giving quotations, Mr. Podhoretz marvels at the temperament of the opposition. “I never imagined that the new anti-war movement would so rapidly arrive at the stage of virulence it had taken years for its ancestors of the Vietnam era to reach.

Such sharp shifts in sentiment here might have been anticipated by considering sentiment in the area of the world in which we were making our stand. A poll published in Kuwait more than two months before September 11 suggested that “69 percent of Kuwaitis, Egyptians, Syrians, Lebanese and Palestinians think bin Laden is an Arab hero and an Islamic jihad warrior.”

Where do we go from here? Mr. Podhoretz tells why the re-election of Bush is enduringly important if we are to persevere in the war that has been declared against ideals with which we were associated in the three preceding world wars. Mr. Podhoretz himself has had profound insights in the past 30 years, speaking wisely and prophetically. He has grounds now to sound the tocsin, but also to express hope.

Radical Islam is not going to renounce what we take to be its ways. But there is, says Mr. Podhoretz, a “very good chance that a clearing of the ground, and a sowing of the seeds out of which new political, economic and social conditions could grow – in the Mideast – would gradually give rise to correlative religious pressures from within. Such pressures would take the form of an ultimately irresistible demand on theologians and clerics to find warrants in the Koran and the sharia under which it would be possible to remain a good Muslim while enjoying the blessings of decent government, and even of political and economic liberty.”

The alternative in November is the election of an ambiguist as president, who would weaken our purpose while enlivening the combative resources of a radical Islamic community that never rose up against the savagery of a great despot, and that now celebrates not those who put him away, but those who seek to emulate him.