Such fears have been highlighted by attacks against 11 mosques around Britain following the killing of soldier Lee Rigby by two suspected Islamist extremists in London.
Campaign groups warn of an increase in Islamophobic and anti-Semitic hate crime in some countries is linked to the declining economy. "The ... economic crisis, which has nurtured the neo-Nazi cause, may endure or worsen," said a report from the World Jewish Congress last month. "We must be prepared for all eventualities."
While violence and tensions have captured headlines, the imams, bishops and rabbis meeting in Brussels accentuated the positive, pointing to religious groups working together to overcome division.
"There is a movement slowly but surely towards resolving these issues," said Syed Ali Abbas, a Shia Muslim representative. "In Europe there is a trend which is moving Jewish, Muslim, Christians and other religions to come together."
In countries hardest hit by the crisis, rising poverty and declining government resources have given religions an enhanced role as providers of basic needs.
"In Spain, Greece, Cyprus, the social services of churches have increased drastically," explains Rev. Rudiger Noll, associate general secretary of Council of European Churches. "If you see how many soup kitchens are offered, it's an unprecedented amount of food that is given out. People are turning to churches for charity."
The Catholic relief agency Caritas said it provided help to 88,000 people in Portugal during the first half of last year, an increase of 64 percent on the same period of 2011. The Orthodox Church in the Greek capital Athens has 3,000 volunteers handing out more than 10,000 food packages a day.
Noll says it's too early to say if such charity or the search for spiritual guidance in a crisis will lead Europeans to return to religion.
In Spain, which keeps monthly figures, that does not seem the case. The number describing themselves as non-believers rose to 16.5 percent from 12.7 percent in 2008.
Despite such numbers, Noll does not see Europe sliding away from religion. In an interview he says organizations from trade unions and political parties to sports clubs are also seeing a membership decline as citizens question entrenched institutions. Beyond that, he says, their underlying spirituality endures.
"Religiosity is not declining. It's relations with the institutional type of church that is declining ... this is the challenge for our churches, they have to open up to modernity and talk to people in today's language if they do not want numbers to decrease."
