He hears it every afternoon - the alien chants of a muezzin summoning a quarter of the local population to the mosque - and he wants to hear it no more. At the edge of Duisburg, a city of half a million in the Ruhr, Pastor Reuter has launched a crusade, sparking a furious debate in Germany about tolerance and the rights of immigrants.
The war, so far fought with petitions, newspaper adverts and a death threat, has exposed almost all German phobias at one stroke: decibels, foreigners and spiritual impurity. Residents worry that the city's bus drivers, mostly Turks, might screech to a halt on hearing the call of the muezzin and lay out their prayer mats in the road. Catholics, whose church is next door to the mosque, complain that the Muslim prayer calls "sound alien to our ears".
Duisburg's Christian Democrats describe the foreigners' demonstrative religious non-conformity as "the last straw", while the Social Democrats worry about the sanctity of law and order. "The religious freedom enshrined in the Constitution applies only to German citizens, not to non-Germans," declared the local SPD leader, August Haffner. The trade unions are angry because no one wants to discuss unemployment any more in a region where one out of five is out of work. Only the Greens are untroubled by the noise pollution.
Earlier this month the city fathers issued a Solomonic judgment, allowing muezzins to exercise their vocal chords at 5pm every day during Ramadan. When the festive season ends, Duisburg's 37 mosques will be allowed to call the faithful at noon on Fridays, but never with loudspeakers.
The matter will not rest there, however, because Pastor Reuter, who was originally only opposed to the electronically amplified din, now wants to muzzle the muezzins altogether. "We are against the Islamic prayer call, because it is anti-Christian in character; because they chant 'There is but one God - Allah'," he explains.
Mr Reuter has produced a pamphlet on the subject, and taken out ads in newspapers. The latest, urging "No Islamic Prayer Call in Public" appeared in the conservative Lutheran review Idea Spektrum.
He is offended by Allah - "a distortion of God" - and is convinced that the muezzins popping up on German rooftops are merely the vanguard of militant Islam, bent on proselytising Christiandom. "There is a world- wide re-Islamisation by fundamentalist reactionary forces," he asserts.
He admits that his "theological stand" has "social dimensions". "A multi- cultural society is fine," he says with disarming honesty, "as long as it is led in accordance with Christian principles." Allowing muezzins to sing to Germany's 2.3 million Muslims would undermine the German way of life.
Although Germany's largest church does not share Pastor Reuter's apocalyptic vision, the turbulent preacher is by no means alone. Money is pouring into a bank account set up to support his cause - the first advert in a local paper cost DM9,600 (pounds 3,650) alone - and most of the community back him. At a public meeting held in the spirit of reconciliation, the Christians easily outshouted the Muslims. A dissenting Lutheran teacher who spoke out against the pastor later received a death threat by telephone.
Pastor Reuter's petition, which accuses the Muslims of violating Germans' individual rights, is to be examined early next month by the city council. The offenders are not backing down, however. Having established that, contrary to the view of the local Social Democrats, "guest workers" are entitled to religious freedom, they are now campaigning for a purpose- built mosque with a minaret. "We want to disturb no one," says Cahit Gedikli, the aspiring muezzin who has so irritated Pastor Reuter, "but they want to hear nothing of foreigners or foreign religions. That's the problem."
Mr Gedikli, like most of the 160 families belonging to the community, is a Turk working in Germany with very little hope of ever obtaining German nationality for himself or his children. The mosque, a ramshackle converted store-room with peeling plaster, receives no grant from the state or the local council. There is no public funding for religious education either, and Muslim customs, such as butchering animals the halal way, are banned and liable to a fine of DM5,000 for every sheep's throat cut.
Muslim leaders argue that the row over the muezzin is merely a symptom of the discrimination they suffer at the hands of German bureaucracy. Christian churches, they point out, are funded through income tax levied by the state, and local authorities strive to maintain a balance between Protestant and Catholic schools. The Muslims do not figure in these calculations, because, as far as the state is concerned, they do not exist, although 7 per cent of Muslims are German citizens.
"The prayer call is not the biggest problem for Muslims," says Ralf Buscher, a German lawyer who converted to Islam 15 years ago and set up his office opposite the mosque. "The real problem is that they don't want Islam here, don't want it in Germany, don't want it anywhere."