Judge Roy Moore was one of the scariest – and most unpleasant – men I have ever met. That he has not yet, at the time of writing, conceded defeat in Alabama is characteristic: clearly only God, not the voters – perish the thought – will defeat him.

My encounter with him was on a hot day in southern Alabama in May 2006, when he was running for nomination to be the Republican candidate for state governor. That was another race he would lose.

Moore had already achieved notoriety in being removed as the state’s chief justice after installing a large stone block carved with the Ten Commandments in the foyer of the state courthouse. It was a clear violation of the constitutional separation of church and state, and Moore had defied repeated instructions to remove it, supported by vociferous demonstrations by the religious right, until finally the supreme court ordered his dismissal from office.

I met him in the small town of Enterprise, which proclaims itself to be Home of the Boll Weevil Monument. Moore did not have the stone with him, though he had been touring the country with it on a flatbed truck as if it were a holy relic, but he was utterly unrepentant.

It is fair to say that the affluent, elderly white members of the local Republican Women’s Club at the Po’Folks restaurant were underwhelmed by his insistence that: “The people of Alabama are goin’ to get the truth and we’re goin’ to do everything to bring it to them, if God wills it.” He made the state capital, Montgomery, sound like Gomorrah, a hotbed of decadence and corruption. There were too many immigrants demanding to take the driving test in Persian, he bizarrely insisted.

Afterwards I was told by his press officer that I could tag along for lunch, but maybe the judge disagreed. His Lincoln sedan roared out of the car park at high speed and barrelled off down the freeway, then crossed the highway and scooted back in the opposite direction, then did another U-turn and another. Struggling to keep up in my little hire car, I decided he was either trying to lose me or was a victim of chronic indecision. Finally we ended up in another car park, at a steak house diametrically opposite where we had started. “Kept up, then?” he asked me, as if disappointed.

In the restaurant, Moore was brusque and charmless, regarding me as he might a stain. He was, after all, the judge who had once placed three children in the custody of their abusive father in preference to their lesbian mother because her homosexuality was “abhorrent, immoral, detestable, a crime against nature, a violation of the laws of nature and of nature’s God”.

You could see why, as a military policeman in Vietnam, he had reportedly earned the nickname of Captain America – his colleagues did not mean it as a compliment – for his habit of prowling around camp at night armed with a sawn-off shotgun in search of marijuana smokers. Not a man for merry banter, then.

Surprisingly, he had not always been a true believer. His Baptist faith came to him only after he had lost his first political campaign to become a district attorney in 1982. It had been a rough fight. “I was done wrong by the political system,” he told me. “After I ran for public office I came to a closer relationship with God. I had hard feelings about people and I prayed about that. God touched my heart and made me forgive them.” It did not sound as if he entirely meant it.

Then he was into a long disquisition about his earthly mentor, who turned out to be the British 18th-century judge William Blackstone, who had been regarded as a little reactionary even in the 1770s. Blackstone believed – like Moore – that God’s law was superior to any other. “All law comes from God,” Moore said. “Human laws are of no validity if contrary to this … no law without God. The truth will spread.” The God they both had in mind was clearly a fundamentalist white Christian one.

Somewhat at a disadvantage, knowing little of Blackstone, I asked Moore whether he had ever been to England. He had not, but he knew we were on the road to perdition, just like America. He signed a little pamphlet he had written, Our Legal Heritage, the cover decorated with the Stars and Stripes: “To Stephen. May God grant you wisdom and understanding of his law and our own!”

The young waitress was nervously eyeing the unconcealed gun sticking out of the holster of Moore’s black bodyguard, Leonard Holyfield, a cousin of the boxer Evander. Moore smiled for the first time, genially at her, and waved her away: “He’s with me.” Then they were off.

Moore, of course, was quite wrong in his belief that America has always been an entirely Christian country: the founding fathers – lawyers themselves and contemporaries of Blackstone – specifically excluded it. They believed more in John Locke and the Enlightenment.

As Thomas Jefferson wrote, lawmakers such as him “meant to comprehend, within the mantle of [the state’s] protection, the Jew, the Gentile, the Christian and Mahometan, the Hindoo, the infidel of every denomination”. It is only in the last 30 years that the religious right has challenged this.

I asked Moore how he would feel if he lost the governor’s primary. “I am not running because of ambition,” he said. “I am running to serve the will of God. If he judges that is not the place I serve him, well, I will probably be happy.” Then he paused and corrected himself: “I will be happy.” A few weeks later he lost that election too. Clearly, it now turns out, the Lord has other ideas.

• Stephen Bates is a former Guardian religious affairs correspondent and author of God’s Own Country: Tales from the Bible Belt (Hodder and Stoughton)