DES MOINES -- Pat Robertson's ability to deliver busloads of evangelical Christians to caucuses should not obscure the real meaning of Iowa: the failure of George Bush's campaign, across the board and in detail.

After subtracting the 26,000 newcomers brought into the process by Robertson, the remaining small universe of Iowa caucus-goers was won by Sen. Robert Dole 2-to-1. That outcome, whose magnitude shocked both Bush and Dole camps, represents a failure of candidate appeal, strategy, tactics and organization.

This repudiation of an incumbent vice president cannot be written off to a ruboff of President Reagan's unpopularity in this deflation-wracked state. The results here undercut the basic Bush concept of riding to an inevitable nomination as the Republican heir apparent.

Despite cautionary warnings from Bush headquarters in Washington that their man could really finish third in Iowa, the vice president's partisans here were still hoping for an upset win. Richard Wirthlin, Dole's pollster, on Monday saw only a 2-to-3 percentage point edge over Bush among ''committed'' Republican voters.

The explosion of Robertson newcomers did not change that. Contrary to the impression conveyed by news reports, it is ludicrous to think that the vice president lost his establishment Republican support to the religious broadcaster.

On the contrary, Robertson's enemy here was neither Bush nor Dole but Rep. Jack Kemp in a contest for evangelical voters. As caucus time neared Monday, Robertson forces were passing out libels about Kemp and his family, the latest being the calumny that the congressman is pro-pornography.

Although he defeated Kemp in the battle for Iowa's religious right, there is no evidence that Robertson -- viewed with hostility and apprehension by old-line Republicans here as elsewhere -- expanded his base Monday.

But he certainly organized it. ''There's something to be said for organizing 600 busloads of delegates,'' Bush campaign adviser David Keene told us, ''when I can't even organize 600 bus drivers.''

That begs the question of why Bush collapsed so unexpectedly. At its heart was the failure of the hard-nosed anti-Dole strategy, seeking to inflame the hot-tempered senator. It may have seemed near the brink of success when Dole railed against the vice president on the Senate floor last week. In fact, it backfired.

A reason for that is Sen. Charles Grassley, Dole's state chairman and by all odds Iowa's most popular politician. In the days before the caucuses, he tirelessly spread the word that Bush's conduct was not in keeping with the state's traditions.

At the same time, the get-out-the-vote organization hurriedly built for Dole by Grassley aide Tom Synhorst outperformed Bush's eight-year veterans -- just as Dole forces had predicted. After months of reading how Bush's organization, controlled by deputy national campaign manager Rich Bond, was an inestimable advantage, the 30-year-old Synhorst exploded in irrepressible shrieks of joy early Monday night when he learned that the television networks were projecting a Dole landslide.

But Bush's Dole-bashing blunders need not be repeated elsewhere, and Dole's organization in other states comes nowhere near the Iowa standard. His supporters here can even take solace in the fact that liberal Republican areas, notably the university community of Iowa City, won by Bush as Reagan's foe in 1980, were lost by him in 1988 as Reagan's vice president. Bush will not carry that burden in Reaganite states, notably New Hampshire.

It is that 2-to-1 margin that hurts. After an issueless campaign during which neither of the two Republican front-runners projected a clear ideological profile, the man who has inexorably emerged over the past eight years as heir apparent was overwhelmingly rejected. A famous re'sume' and a record of loyalty are not enough, even for Republicans. The inevitability of George Bush, however illusory from the start, was destroyed in Iowa Monday night.