And 58 per cent of those questioned were happy about using porn for sexual stimulation, a UK survey of religious and secular attitudes to sex suggests.
A YouGov online poll of 4437 adults found that the respondents who described themselves as religious felt more guilt than those who were non-religious.
But the organisers of the poll suggested that "Roman Catholic guilt" was a "myth": they saw "no evidence that Catholics feel more guilty about sexual 'sins' than other religious people".
Baptists, Muslims, and Pentecostals were those who felt it most. For example, almost nine out of ten Baptists would feel guilty over sex outside marriage.
It found that 89 per cent of the Roman Catholics who were polled did not feel guilty about using contraception.
The survey was part of research into the notion of guilt by academics at Lancaster University's Religion and Society Programme, which organises the Westminster Faith Debates.
The Professor of the Sociology of Religion at Lancaster University, Dr Linda Woodhead, said this week that the survey identified a strain of "puritan guilt" that survives in modern Britain.
She said that many Roman Catholics appeared to have distanced themselves completely from their Church's teaching.
"It doesn't mean that they are not going to church, or sincere believers, but they are not in the mould that the church hierarchy would like them to be. It is particularly concerning for the Church because it has really staked its distinctiveness on sexual morality."
Those who felt "least guilty" over the sexual activities about which the survey asked were men who regarded their own judgement or intuition as authoritative; did not identify with, or participate in, a religion; and were definite about their belief that there was no God.
In contrast, those who felt "most guilty" were women who described themselves as religious, were active members of a religious group, and definitely believed in God.