Humanists have attacked the religion question in the 2011 census for being "fatally flawed" because it is "highly misleading" and does not help with the planning of public services.

In a British Humanist Association poll, 61% of 1,896 adults in England and Wales said they belonged to a religious denomination or body. When asked in a subsequent question if they were religious, only 29% of the same people said yes.

It also showed that 48% of the people interviewed who said they were Christian believed that Jesus was a person.

Asked how often they went to a place of worship for religious reasons, 63% of respondents said they had not done so in the past year, while 20% said they had never visited a place of worship for religious reasons.

The BHA poll comes days ahead of the 2011 census on March 27, which has estimated costs of £480m and a workforce of 35,000.

Secularists and humanists oppose the voluntary question on religion – featured for the first time in the 2001 census – because they claim the data is used to "justify" religious privilege in state policy on public services.

Today BHA chief executive Andrew Copson said its poll was "further evidence" the census data was "highly misleading" because it gave an inaccurate representation of religiosity in the UK.

"We urge people who do not want to give continuing or even greater importance to unshared religions in our public life to tick 'No Religion' in the census."

Earlier this month its census campaign posters were banned from railway stations because the slogan – "If you're not religious, for God's sake say so" – was deemed likely to cause serious and widespread offence.

"We used to tick 'Christian' but we're not really religious. We'll tick 'No Religion' this time. We're sick of hearing politicians say this is a religious country and giving millions to religious organisations and the pope's state visit. Money like that should go where it is needed," says one of the banned posters.

The ban, initiated by companies that own advertising space in stations, followed advice from the Advertising Standards Authority.