The government is dragging its feet on legal recognition of humanist weddings despite growing demand for such ceremonies, the television scientist Prof Alice Roberts has said.

Roberts, who is president of Humanists UK, called for the process of changing the law to be accelerated. “More and more people are turning to a humanist way of marking the milestone events of life: the birth of a child, celebrating a marriage and remembering a loved one,” she said. “The government said a couple of years ago that it would make humanist weddings legal, but it has dragged its feet.”

In Scotland, where humanist celebrants have been permitted to conduct weddings since 2005, there are more humanist weddings than weddings in the Church of Scotland and the Catholic church combined, she added. “The government needs to make this happen soon.”

In England and Wales, couples opting for a humanist ceremony have to undergo a separate legal wedding in a registry office. Nevertheless, Humanists UK – of which Roberts is president – recorded an almost fourfold increase in such ceremonies between 2004 and 2012, while Church of England weddings fell by 28% and Catholic weddings by 34% in the same period.

Roberts is anchoring a new online course, Humanist Lives in which scientists, artists, politicians and campaigners explore humanist beliefs and values.

“Humanism is much more than an absence of faith. It’s a positive belief in humanity and the power of rational inquiry; a framework for how to live your own life and create a better, fairer, more inclusive society,” said Roberts.

“It would be helpful if humanism was more widely recognised. We are a largely non-religious society, with a very small number of people going to church every week – well under a million regular churchgoers in the C of E, fewer than members of the RSPB [Royal Society for the Protection of Birds].

“Yet we still have an established church in a diverse multicultural society, with reserved places for Anglican bishops in the House of Lords, and the C of E extending its reach and influence into education. It would be better if religion was not tied up with the state.”

Roberts, a biological anthropologist and television presenter, grew up in a deeply religious family, but gave up going to church when she was 15. In recent months, she has been criticised for sending her children to a Church of England primary school, and her mother, a retired teacher, has publicly challenged her opposition to faith schools.

“Like so many parents, I had no choice about where my children went to school,” she said. Her children did not get places at non-religious schools near her home, leaving no alternative to a faith school. “We want all local schools to be inclusive, community schools.”

She also wants BBC Radio 4’s Thought for the Day to be opened up to humanists – and to be the first to present the item. “You can have a view on ethics and morals from a non-religious rational perspective. I get so frustrated when the religious and theological view of morals and ethics is privileged over non-religious perspectives. It’s deeply anachronistic.”