On Tuesday, offices around the UK will look particularly empty. No, not because of another Lehman Brothers-type crash in the market, though in these uncertain times that possibility cannot be ruled out entirely, but because Tuesday marks the feast of Eid al-Fitr, when Muslims celebrate the end of Ramadan. It is also the first day of Rosh Hashanah, the Jewish New Year. Both holy days involve festive meals, praying, and spending time with family and community.

Absence from work on holy days is, however, only one manifestation of the relationship between faith and work. While once believers kept faith and work relatively separate, now they are increasingly intertwining. With the growth of mass migration the UK’s population has become more diverse, and its labour market, in consequence, multifaith rather than, as once was the case, predominantly Christian. In London alone, there are 42 nationalities with communities of more than 10,000. It is now common for people to work in environments with at least one person from another religion or ethnic background.

This makes the workplace an inadvertent forum for interfaith encounters. In July, for example, the Muslim banker Naguib Kheraj was appointed chief executive of the City institution JP Morgan Cazenove, and commented: “In the City of old you wouldn’t expect to see someone of my background coming to run a business like this.”

Alongside the higher profile of a diversity of faiths in the workplace, believers increasingly show signs of wanting to integrate faith and work. Ken Costa, the committed Christian who is one of the City’s best-known investment bankers, has argued that “if the Christian faith is not relevant in the workplace, it is not relevant at all”.

Whether through dress, dietary requirements or prayer, believers appear increasingly to want to be able to express their faith in the workplace. On the other side of the equation, companies are becoming more sensitive to the faith-specific needs of their employees. This trend is partly driven by new legislation on religious discrimination at work, introduced in 2003.

Between March 2007 and April 2008, alone, 600 cases of workplace discrimination on religious grounds ended up in the courts, and a number of media reports have highlighted instances of perceived religious discrimination at work. Last year, for instance, British Airways found itself in the midst of a media storm when it stated that that an employee who wore a cross was violating the company dress code and when she refused to stop wearing it, she lost her job. This decision, which the Archbishop of Canterbury labelled “deeply offensive”, was eventually reversed.

Legal issues aside, many companies are now taking active steps to become faith-friendly. According to a Chartered Institute of Personnel and Development survey in 2007, one-third of companies are developing explicit policies on managing religious beliefs in the workplace. Dianah Worman, the CIPD’s diversity adviser, says:“Generally the issue of diversity is rising up the agenda of business, and faith is part of that. Business needs to be responsive to it and manage the practical issues sensibly and fairly as high profile media cases have shown.” In addition, there is an Employers Forum on Belief for companies to share best practice on faith-related issues.

Furthermore, many large companies whose employees represent a wide range of religious belief now have faith and ethnic networks. These provide prayer services, educational programmes and festive celebrations.

Clifford Chance, the international law firm, has active faith networks including Christian, Muslim and Jewish groups, all of which organise lunchtime events and various other activities. The leading accountancy firm PricewaterhouseCoopers has four faith-specific networks, each of which is led by a partner and assigned a budget. In the US, the existence of such networks is commonplace ( an estimated 10,000 Bible and prayer groups exist in the US), and they are now becoming a growing feature of large corporations in the UK. Prayer rooms, once consigned to hospitals and airports, are now increasingly common in offices.

Being faith-friendly increasingly appears good business sense.When law and accountancy firms pitch for work, they are sometimes asked for diversity statistics. In finance, banks have been seeking to capitalise on the opportunities offered by Islamic banking. The Islamic finance industry is said to be worth $700 billion, and there is potential for further growth, given that Muslims account for 20 per cent of the world’s population, but Islamic finance presently constitutes less than

1 per cent of global finance. Another faith-based investment are financial stocks compatible with Hindu and Buddhist beliefs such as the Dharma Index, launched by Dow Jones in 2008. Religious scholars vet the labour, environmental and other relevant company policies to see if they are compatible with their religious tradition.

All this does not mean an absence of conflict between God and Mammon, especially in issues of business conduct and ethical behaviour. From the illegal activity of Enron to business practices that raise moral dilemmas, for example, the use of child labour, faith groups can sometimes find it hard to reconcile ethics and trade.

However, companies are often taking into account ethical considerations in their behaviour, and corporate responsibility is on the rise. This has been reinforced by the work of faith groups, who are increasingly promoting good business practice and responsible wealth creation. Almost 200 people attended the Christian Association of Business Ethics’ annual lecture in the City in 2007. Meanwhile, its Jewish equivalent, JABE, promotes ethical business practice in schools and synagogues. Ethical business is also high on the agenda for global religious leaders. The Dalai Lama’s book Ethics for the New Millennium addresses this subject, while this autumn, Pope Benedict XVI is expected to issue an eagerly anticipated encyclical on capitalism.

Faith and business do not necessarily have to be reluctant partners, they can reinforce each other. Recent research by the management consultant firm McKinsey Australia shows that companies which embrace “spiritual techniques” benefit from improved productivity and turnover. In any case, as current trends develop, faith looks set to become an issue for the boardroom.

Zaki Cooper is a consultant to the Cambridge Interfaith Programme, a trustee of the Council of Christians and Jews and the Director of Business for New Europe