Willis squirms. During the recent media splurge to launch the down-at- heel Cock and Bottle as Britain's first Christian-run pub, the whole point was to present the bar as normal - though the staff are unpaid volunteers - and those running it as ordinary blokes, not wide-eyed, teetotal Bible- bashers.
When a hymn unexpectedly drifts from the sound system, Willis scuttles off and puts on something by M People instead. Eager to quash any misconceptions, he insists that the pastor is a drinker. Oh yes. Definitely less a Nescafe than an Old Speckled Hen man.
These days, image is all. Nowhere more so than in this inner-city pub whose raison d'etre is to spread the word of the Lord but, in a secular age, needs to employ a little subtlety lest the punters take to the hills before their conversion is complete.
Sitting in a corner of the crowded Victorian bar, which is situated between bleak high-rises and the Balti Express takeaway, Gamble, special adviser on evangelism to the Bishop of Bradford, recalls how he was pulling pints behind the bar when a local strode in. "The bloke took one look at me wearing my dog collar and walked right back out again."
Gamble argues that his aims are gentle - to reach out with the love of God. He promises: "No one who pops in for a pint will have religion rammed down their throats." The consortium has pledged that "Christian entertainment" evenings will take place in function rooms, and one-to-one sessions with tortured souls in cosy side snugs, and that God will not be mentioned in the bar unless the punter brings Him up.
It is an odd division, which may blur with time: "No one is selling Jesus in the pub," insists Willis, a self-confessed womaniser who was himself "saved" only a few years ago.
Jesus is certainly being flogged on the side. Only last week, Willis took a drunk home, after refusing him alcohol - "the pubs' standard practice with drunks" - and suggested he might get down on his knees and talk to the Lord, an interesting variation on the usual "go home and sleep it off" approach.
It is a tough call, modern evangelism. In other parts of the country pastors have turned to gimmicks such as training as clowns and fire-eaters and even offering spiritual advice in rave clubs, to spread "and sugar" the Word.
Gamble pioneered after-pub teaching in Bradford city centre. "There were a few hairy moments," he admits, when drinkers pelted him with bottles.
He has been exploring the pub idea for a few years, and hit the jackpot when Enterprise Inns was struggling to find a way to rehabilitate the unwanted Cock and Bottle. The inner-city bar had earned its rough reputation. The beautiful stained-glass windows were regularly shattered during brawls and a few years back the pub landlady killed her violent partner on the premises.
The Christian consortium has spiritually cleansed the premises, praying in every room. Tonight, "those of the congregation" are out in force, but it is too early to say whether they will be able to pull the locals in.
Some old regulars are now back in their old corner of the bar. They have not heard Willis describe the pub - in another emotional departure from their "just an ordinary bar" script - as a "Christian mission station". And they are entirely nonchalant about the new operators, and any possibility that the Christian consortium is simply luring them in.
"It hasn't put me off a bit," said Cathy Morton, 48, a "weddings and funerals" Christian, and a Cock and Bottle regular for the last 10 years. "All that matters is what they have done for the bar. The renovation is great and so is the new atmosphere. It's wonderful not to have to worry about the fighting."
The Metcalfs - Alma, 75, and Bob, 77 - have been regulars for 30 years; they live across the road. "It's great," said Mrs Metcalf. "Local people feel safer coming in now." She said there are a lot of unfamiliar faces - presumed to be "of the congregation" - but she adds that everyone is mixing well.
Even Bradford's Muslims appear to have been won over. A local Muslim taxi driver reveals that he has started to frequent the pub - for soft drinks only - since the Christians made it safe again.
So far, the only hostility has come from a small Evangelical church dismayed that Christians should have taken to the bottle. It all hinges, of course, on whether you believe that Jesus would have been up at the bar, or protesting outside against people coming in.
The Christian consortium has no doubt. The Lord would have been with his people, propping up the bar.