Graham Greene's religious faith was often fragile. When in one of his periodic moments of doubt he suggested to Evelyn Waugh that he was considering resigning from the Catholic novelist coterie to which the two belonged, Waugh was outraged and insisted Greene carry on writing novels with a religious basis, however uncertain his belief had become.

While it is generally considered Greene's Catholicism is no disincentive for agnostic or atheist readers, there are those who have problems with the religious underpinnings of one of the great American crime novelists, James Lee Burke. In the novels featuring his troubled private investigator Dave Robicheaux, there is an element that gives Burke naysayers ammunition. The detective's ex-nun partner provides (simultaneously) raunchy sex and a strong sense of the spiritual - a phoney attempt (it's claimed) to have the best of all worlds from a sensualist/believer such as Burke, or Greene.

Faith is at the heart of Burke's new novel, but this time there is no attempt at proselytising. Religion here, largely speaking, is of the gun-toting, un-nuanced kind that has hijacked Republican politics in the US.

As with another American writer who combines extreme violence with poetic lyricism, Cormac McCarthy, Burke's stamping ground is deep South West Texas, and the locales of Feast Day of Fools fairly leap off the page in pungency and bitter vigour. We are once again in the company of Sherriff Hackberry Holland, a Korean War vet, dispensing his precarious line of law enforcement near the border with Mexico.

As in earlier Holland books (notably Rain Gods), his universe is surrealistic and minatory. We are given another monstrous villain in the psychotic preacher Jack Collins, along with the equally terrifying mercenary, Krill. And Burke is even audacious enough to up the ante with another psychopath, the illiterate Negrito, along with the psychologically troubled Rev Cody Daniels (who enforces the power of the Scriptures with the barrel of a gun). Holland struggles to deal with all these antisocial characters, along with gunrunners, drug smugglers and an enigmatic Chinese woman, 'La Magdalena', engaged in smuggling Mexicans into the US.

Even more than in previous Burke novels, this is a heavily loaded, overwrought narrative, and it's a measure of the author's skill that he always succeeds in persuading us of the reality of this crazed world. His efforts are couched here in the customary poetic prose and - Burke detractors should note - there is no attempt to freight in propaganda for the benefits of God's grace. Religion here, as in most of the best thrillers, is a dangerously destabilising force rather than a source of salvation.