The pretty spa town beside a winding river is getting ready for Christmas. A Santa Claus statue stands near the main square, tinsel decorates shop windows and at medieval St Paul’s Church carols will soon be sung by enthusiastic worshippers.

A stroll from this festive scene in Bad Kreuznach in Germany, 33-year-old Aline runs an estate agency, letting out houses and flats from a smart office. A few weeks ago she received a call from a man who, in faltering German, said that a newly arrived Syrian migrant family was looking for a home.

Aline agreed to show the family an empty four-bedroom apartment but, when she arrived at the address, the group of three men, a veiled woman and a gaggle of children suddenly said they had ‘no interest’ in viewing the place.

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Divided: Chancellor Angela Merkel controversially opened the borders to Germany in August, to all Syrian refugees. But thousands of economic migrants have also seized the opportunity to enter Europe. Pictured, migrants and refugees walk to a train in Passau

Worry: Many German citizens are concerned that their country is facing a population time bomb, with thousands of refugees and migrants still arriving on a daily basis

The reason? Apparently, they had taken against her for being female. Aline, a blonde and confident businesswoman, had also made eye contact with one of the men. With that, the Syrians asked for a male estate agent.

‘It was quite shocking to me,’ says Aline. ‘I was really upset. You want to help, then you’re sent away unwanted in your own country.’ After writing of her experience on Facebook, she received two death threats calling her a ‘Nazi bitch’. They were not posted by migrants, but by Germans claiming she was racist for criticising migrants.

Her story in this provincial town, where hundreds of migrants are staying in hotels and camps before being given rental accommodation, is one of many dividing German opinion over mass migration.

In August, when Chancellor Angela Merkel controversially welcomed all Syrians, promising them asylum, benefits and housing as war refugees, the country’s mood was buoyant. Helping out was the right thing to do, said most Germans.

I was really upset. You want to help, then you’re sent away unwanted in your own country. Estate agent Aline, 33

But other faraway nations, such as Pakistan, Afghanistan, Iran, Iraq, Algeria, Morocco and Egypt, took note of Mrs Merkel’s message. Within weeks, thousands of migrants, only 20 per cent of whom are believed to be Syrians, had grabbed the chance of a new life in the West. In what has become the biggest European movement of people since World War II, countries from Sweden to Hungary have hurriedly introduced border checks to try to assess who are genuine refugees.

Yet each day 7,000 migrants still arrive in Germany. They are predominantly young Muslim men from the Middle East, Africa and even the Balkans, and their numbers have topped 180,000 since the beginning of this month — equivalent to the population of Luton.

By the end of 2015, a million new migrants will have reached Germany — a nation of around 80 million — in a year, most after paying huge sums to people smugglers for dangerous crossings from Turkey to Greece en route to Mrs Merkel’s land of milk and honey.

The surge of new arrivals is likely to reach the same tally in 2016.

Family: By the end of 2015, a million new migrants will have reached Germany. Pictured, a woman and her children waiting to cross the Greece-Macedonia border in the rain, near Gevgelija

Newcomers: Migrants and refugees arriving in Germany are predominantly young Muslim men from the Middle East, Africa and even the Balkans, and their numbers have topped 180,000 since the beginning of this month

Threat: A total of 150 fires were started by arsonists in migrants’ shelters in the first six months of this year. Pictured, migrants and refugees after crossing the Austrian-German border near the Bavarian village of Wegscheid

Journey: Former interior minister Hans-Peter Friedrich, a member of a sister political party to Merkel’s CDU, warned that they can only unreliably estimate how many of those arriving in the country are ISIS fighters

Demographers at the Bavarian Association of Municipalities say Germany faces a population time bomb. As migrants bring in wives and children, they warn that the number of Muslims could rise from 5.8 million to 20 million by 2020, threatening the culture of this once fiercely Christian nation.

And some have not taken kindly to the influx. Hardly a day passes without an attack on immigrant camps, homes or hostels.

A total of 150 fires were started by arsonists in migrants’ shelters in the first six months of this year — before the dramatic surge in arrivals that began after Mrs Merkel’s August announcement. Germany’s domestic intelligence chief, Hans-Georg Maassen, says: ‘What we’re seeing is the street mobilisation of Right-wing extremists, but also of some Left-wing extremists who oppose those anti-immigration groups.’

What we’re seeing is the street mobilisation of Right-wing extremists, but also of some Left-wing extremists who oppose those anti-immigration groups. Germany’s domestic intelligence chief, Hans-Georg Maassen

Frontex, the European border agency, and Western intelligence services have sounded a second alarm. They warn that Islamic State jihadists are exploiting the refugee influx to slip into Europe.

Former interior minister Hans-Peter Friedrich, a member of a sister political party to Merkel’s CDU, said recently: ‘We can only unreliably estimate how many of them are Islamic State fighters or Islamist “sleepers” . . . no other country in the world would be so naive and starry-eyed as to expose itself to such a risk.’

Yet Mrs Merkel sticks to her plan. ‘I have my vision and will fight for it. All is under control,’ she said of the migration crisis on TV recently.

In a 40-minute speech this week, she urged Germans to carry on as normal despite the Paris attacks by Islamic State fanatics. ‘We Europeans will show our free life is stronger than terror,’ she said.

But even though ‘Refugees Welcome’ signs dot every German town and city, many are growing nervous about what’s coming next.

A respected TV station, N24, has reported that many new arrivals have already vanished under the radar since entering the country. On three occasions in September, groups of young male migrants, thought to be non-Syrians trying to escape the attention of immigration or security services, have pulled the emergency brakes to stop trains taking them to camps for registration, then jumped out and vanished.

Meanwhile, German police say they are investigating 60 cases in which Islamic extremists, some posing as charity workers, have infiltrated migrant camps to recruit migrants to jihad.

In a 40-minute speech this week, Ms Merkel urged Germans to carry on as normal despite the Paris attacks by Islamic State fanatics. ‘We Europeans will show our free life is stronger than terror,’ she said. Pictured, stranded Iranian migrants on hunger strike at the Greece-Macedonia border

Migrants and refugees walk along a street after passing the Austrian-German border near Wegscheid, Germany

A leaked document by German intelligence chiefs warned that fully integrating hundreds of thousands of what it termed ‘illegal migrants’ will be ‘impossible’. Pictured, migrants and refugees being escorted by German police to a registration centre near Passau, Germany

Three weeks ago, the Refugees Welcome organisation in Bonn made an embarrassed online apology for incidents of sexual harassment that happened, ironically, at a party it helped organise to make migrants feel at home

But terror is far from the only worry on German minds.

It is bitterly ironic that postwar Germany, still battling with national guilt over the Nazi slaughter of six million Jews in the Holocaust, is importing so many people who are avowedly anti-Semitic.

A leaked document by German intelligence chiefs warned that fully integrating hundreds of thousands of what it termed ‘illegal migrants’ will be ‘impossible’.

It added: ‘We are importing Islamic extremism, Arab anti-Semitism, national and ethnic conflicts of other peoples, as well as a different understanding of society and law.’

The document, published in the heavyweight Die Welt newspaper, added: ‘Intelligence agencies cannot cope with these problems, [or] the response from the German population.’

We are importing Islamic extremism, Arab anti-Semitism, national and ethnic conflicts of other peoples, as well as a different understanding of society and law. Leaked document by German intelligence chiefs

Those views were echoed by Josef Schuster, president of the Central Council of German Jews, this week.

In a careful statement, he said: ‘Many flee from Islamic State terror to live in peace and freedom. At the same time they come from cultures in which a hatred of Jews and intolerance is a fixed element. Don’t only think of Jews, think of the equality of woman and man or dealings with homosexuals.’

Even charity workers have been horrified by the behaviour of some of the new guests. Three weeks ago, the Refugees Welcome organisation in Bonn made an embarrassed online apology for incidents of sexual harassment that happened, ironically, at a party it helped organise to make migrants feel at home.

It said: ‘We observed that some men molested, touched and harassed women. We tried to identify the offenders and make them leave, and also made announcements asking them to stop this behaviour immediately.

‘However, these measures were not successful. These men cast a negative light on our organisation as well as on all men and male refugees at our party.

‘We believe in respect between human beings … and that includes accepting a “No” instead of forcing your will on another person.’

If Germans are struggling to cope, so, too, are the migrants. In overburdened hospitals (faced with an increase in diseases more commonly seen overseas, including tuberculosis), many of them will only see male doctors, while women insist on being examined by females

A woman and her children walk past Macedonian police officers, as migrants and refugees cross the Greece-Macedonia border on November 27

There have been riots, too. In Calden, a town in central Germany, residents gave a warm welcome to migrants, collecting clothes for them and providing food parcels

Meanwhile, Jurgen Mannke, director of the Teachers’ Association of Saxony-Anhalt, in central Germany, has said girls must be warned against consorting with Muslim migrants.

He wrote in a magazine: ‘It is our human duty to help people who are facing existential distress due to war and political persecution.

‘But it is extremely difficult to distinguish who comes to our country for purely economic or even criminal motives. From our ethical and moral perspective, women are not treated equally or with dignity in Muslim countries. Already, we hear . . . about sexual harassment on public transport and in supermarkets.

‘As responsible teachers, we ask ourselves: “How can we enlighten our young girls aged 12 and over so they do not engage in superficial sexual adventures with often attractive Muslim men?” ’

If Germans are struggling to cope, so, too, are the migrants. In overburdened hospitals (faced with an increase in diseases more commonly seen overseas, including tuberculosis), many of them will only see male doctors, while women insist on being examined by females.

It is our human duty to help people who are facing existential distress due to war and political persecution. Jurgen Mannke, director of the Teachers’ Association of Saxony-Anhalt

Among the litany of complaints from migrants are that Germany is too cold, the food isn’t spicy enough, there is no cigarette money, the internet connection is too slow, jobs are difficult to get and the orange juice served in camps is too sugary.

There have been riots, too. In Calden, a town in central Germany, residents gave a warm welcome to migrants, collecting clothes for them and providing food parcels.

Volunteers from the fire department helped to build a tent city on the outskirts, near the small airport, where nearly 1,000 now live. But in September, 50 police fired tear gas to stop 400 migrants fighting each other using chairs and tables as weapons after a row broke out between a Pakistani and an Albanian in a meal queue.

The local grocery store has hired security guards because of pilfering and mayor Maik Mackewitz has lamented that women no longer go jogging in the woods because they are afraid of attacks.

One mother says her 17-year-old daughter was ‘sexually harassed’ at the bus stop by young migrant men waiting to take a ride to the shops. ‘Of course we are scared,’ she told Mr Mackewitz.

Outside the camp this week, I found Mohammad Niksira and his wife Monira walking back, on a bitterly cold day, from the guarded grocery store. They have been here for less than a month, but already get £50 a week each in benefits from the Government as well as a free roof over their heads.

Both 28, they come from Iran’s capital, Tehran, where Mohammad worked as a swimming pool lifeguard. They are clearly not refugees fleeing war, and admit it.

When a BMW factory in Bavaria reserved 20 job places in its logistics department for the newcomers this year, there was not one applicant with ‘the necessary skills or a desire to work’

Demographers at the Bavarian Association of Municipalities warn that the number of Muslims could rise from 5.8 million to 20 million by 2020, threatening the culture of this once fiercely Christian nation

‘In my country, we don’t have freedom of speech or an economy where we can make money. That is why we came here. I want to work and be rich,’ he says.

‘The camp is full of Syrians, Iraqis, Albanians, Afghans, Africans and a few Iranians,’ he adds in good English. ‘But we will have a house of our own very soon. The German authorities have told us so.

‘We have friends from Iran who came to Germany just before us. They have houses already. When we get one, we are going to have a baby,’ he adds, smiling at Monire, who covers her face with a scarf so I can only see her dark eyes.

Mohammed may have what it takes to succeed, but few migrants are capable of holding down steady work. Just 8 per cent have an academic qualification, while 81 per cent do not have any qualifications or skills, says the Federal Employment Agency.

The women are unlikely to be encouraged into employment by their families. As one 21-year-old Syrian migrant told me this week in Bonn: ‘An Arab wife’s place is at home, doing the cooking and looking after children.’

When a BMW factory in Bavaria reserved 20 job places in its logistics department for the newcomers this year, there was not one applicant with ‘the necessary skills or a desire to work’.

The local official organising the scheme added: ‘Many seem to believe that in Germany everyone is rich, has a job, an apartment and a car. They have the idea that we were here waiting to create the same life for them.’

Back in Bad Kreuznach, I visited Aline in her office, wishing to talk about the Syrians who apparently spurned her just for being a woman.

At the front desk I asked her secretary to pass a written note to Aline, saying I had come to see her. A few minutes later the assistant returned, my message still in her hand. ‘Aline is now too afraid to speak to you, or anyone, about this incident,’ she said.