By RAY WADDLE Today’s most influential evangelical leader, radio psychologist James Dobson, comes to town next month, dissatisfied. He has lately voiced impatience with Republican leaders for doing little to reward Christian conservatives who helped elect President Bush in 2004. The crusades against abortion and homosexuality look stalled. The values-voter bloc, battle-tested and triumphant two years ago, appears empty-handed, disillusioned. But Dobson says a Democratic victory would be worse, so he is here Oct. 16 to rally religious voters to keep conservatives in congressional power. It is a familiar (media) story by now -- fearsome Christian vitality, then disillusionment with politics, then revitalization, then disappointment, then regrouping, again and again and again. A decade ago, disgusted after Bill Clinton’s resilient re-election, some evangelicals strategists publicly urged believers to quit politics and get back to evangelism. By 2000, they forgot the advice and mobilized again to do battle for Bible and civilization. Religious ambivalence to politics -- dreams of power, yet distaste for compromise -- makes for cranky mood swings and mixed signals, an impatience with real-world conditions. It makes me nostalgic for Reinhold Niebuhr (1892-1971). We never see theologians on newsmagazine covers anymore. Celebrity-ready religious leaders now come from the media world; Dobson oversees a radio-and-publishing empire in Colorado Springs. But in 1948, Time Magazine featured Niebuhr out front. He was, for a few decades, the most influential Christian theologian of the Cold War. A Niebuhr revival is astir. Opinion-shapers are rediscovering him as a tough-minded Christian realist (or hawkish liberal) alert to human illusions. He distrusted the corruptions of power but ridiculed naive pursuits of doctrinal purity. He said we must willingly use power for moral causes while staying wary of our own pretensions. (He would have blistered Bush for his axis-of-evil condemnation of Iran and North Korea. The presidential rhetoric won purity points but childishly worsened diplomatic avenues we need now.) Missouri-born, Niebuhr ministered a Protestant church in Detroit in the 1920s but was ultimately drawn to public policy and scholarly writing about good and evil, God and politics. (His books include Moral Man and Immoral Society and The Irony of American History.) Conservative columnist David Brooks woke up to Niebuhr after 9/11: ”Religion is a crucial driving force of this century, and Niebuhr is the wisest guide,” he wrote recently. He quoted political scientist Alan Wolfe: if everyone read Niebuhr, “the devout would learn that public piety corrupts private faith and that faith must play a prophetic role in society. The atheists would learn that some people who believe in God are really, really smart. All of them would learn that good and evil really do exist,; and that it is never as easy as it seems to know which is which.” Niebuhr avoided cynicism, hysteria and sentimentality, the trinity of manic politics. He believed in sin. And courage. And faced down the complications of this political planet without flinching.