For many Republicans, what matters most about Donald Trump is that he’s demonstrated resolve against the enemy — not the Islamic State or the Taliban, but the media.

The media has become for the right what the Soviet Union was during the Cold War — a common, unifying adversary of overwhelming importance. Before the fall of the Berlin Wall, religious conservatives and libertarians could agree that, whatever their other differences, godless communism had to be resisted. This commitment was the glue of the GOP coalition, and the basic price of admission to conservatism.

Now, a policy of containment, preferably rollback, of the mainstream media occupies that central role. Trump may not be delivering on his agenda, but he’s a righteous, unyielding warrior against the media. And this is the one nonnegotiable. To put it in terms of the famous Isaiah Berlin essay, the fox knows many things; the hedgehog knows one thing — CNN stinks.

The right’s hostility toward the media is long-standing. In fact, no one has improved on what Spiro Agnew said in a famous speech in Des Moines, Iowa, in November 1969, or even really said anything new.

Agnew complained that after President Richard Nixon gave a televised speech, his words were instantly subjected to “querulous criticism.” He pointed out that the media is in a bubble, living “in the geographical and intellectual confines of Washington, D.C., or New York City.” And he wanted to limit the power of this “small and unelected elite.”

Newt Gingrich demonstrated the transformative potential of theatrical attacks on the media in his show-stopping performances at two South Carolina primary debates in 2012. He wouldn’t have won the state without them.

Trump’s insight was basically, “What if every day were like that?” After witnessing the fate of two candidates who got savage coverage in the general election, despite being a media darling in the case of John McCain and being an earnest, well-meaning man in the case of Mitt Romney, Republican voters were ready for harsher stuff.

Trump had long had his own problems with the media, namely that it wasn’t nearly favorable enough to Donald Trump. With his talents as a showman, his taste for combat and his instinct for what energizes an audience, he was ideally suited to transfer his long-developed personal sensitivity to slights from reporters to the ideological realm of Republican presidential politics. In large part, he rode his mutual enmity with the media to the White House.

It remains a lifeline. Most commentators saw Trump angrily saying indefensible things about Charlottesville at the news conference last week; most Republicans saw him gamely standing his ground in front a group of braying reporters. At his rally in Phoenix, Trump upped the rhetorical ante and used the media’s lack of credibility to try to undermine the critique of his Charlottesville remarks.

It helps him that the press is, indeed, worse than ever before. As the media environment has fractured, organizations feel less obligation to try to cultivate a broader audience. And as politics becomes more culturally charged, the divide between the heartland and the coasts where the media lives and works becomes important.

Then there’s the reaction to Trump himself. Since he is genuinely outrageous, especially to coastal sensibilities, the media feels justified in its unremittingly harsh coverage.

The war with Trump also serves the twin goals of self-referentiality and ratings. CNN at times appears to be a network devoted to covering things that the president says about the network. Prior to Trump’s rally in Phoenix, CNN relentlessly promoted the event. Then it broadcast the whole thing and devoted the rest of the night to commentators pronouncing themselves outraged and dismayed. At the end of the day, what had really happened? Nothing much, but at least something entertaining had filled the air.

Trump might well have been hate-watching much of it, pleased somewhere beneath his anger and disgust that he had, once again, proved to have the right enemy.

Rich Lowry is a syndicated columnist. He can be reached via e-mail at: comments.lowry@nationalreview.com.