It was important, he said, that people of faith “are prepared to speak up and speak out from the position of faith”.
“In other words, we’re not afraid to say this is why we believe what we believe and not be embarrassed about it or think there is something strange in saying that,” he said.
Taking part in a debate in Westminster about faith in public life, Mr Blair laughed as he recalled the instruction from his then press secretary, Alistair Campbell, not to “do God”.
He also admitted that he had once ordered two reluctant aides to get down on their knees in prayer during a meeting with members of the Salvation Army.
“One thing I loved about meeting such people when I was in office was their unashamed proclamation of faith and I think that’s important,” he said.
Mr Blair denied praying with former US President George Bush but added that it would “not have been wrong to do so”.
He said he still did not agree with the position of some Christians, including the Salvation Army, on the issue of gambling and supercasinos, but stressed that faith groups should have the right to put their views forward.
“I don’t think there should be any restraint on religious people putting forward their view and saying ‘I’m doing this because I actually believe it to be part of my religious belief’. I think they are absolutely entitled to do that. But the quality of the discourse and the way in which it is conducted is really, really important,” he said.
Mr Blair also spoke of the importance of telling others about the good work being done by people of faith in the UK and overseas.
“I think the people who are pushing this aggressive secularism, they have a common cause with people who are very extreme about their own religion, because provided the face of religion is extremism, it is easy for the secularist to say ‘Oh, I told you, they are all crazy people, you shouldn’t listen to them’,” he explained.
Mr Blair was debating faith in public life with the Archbishop of Canterbury, Dr Rowan Williams.
Dr Williams said he worried Britain was moving towards a “climate where people seem to assume we all really know what’s rational but unfortunately a few religious people complicate matters”.
“We are in danger of assuming that morality is self-evident, that there is an absolutely obvious default setting that is secular and ration and objective for discussing moral questions and therefore what religious people think about human nature or human behaviour is just an eccentric extra,” he said.
The Archbishop urged caution, however, in painting Christians as the victims. He said he was not sure people of faith who feel victimised or marginalised “always see it clearly”.
“I think a few extremely difficult areas and a few extremely hard cases have created a highly coloured view of where we are,” he said.
“I’m just a little wary of jumping too quickly into the victim posture here. As religious communities we have access to the public sphere.
“We can be visible and audible in public discourse and I would say that over the last decade or so, the recognition that religious motivation is really significant across the board for an awful lot of people has made it perhaps a little bit less disreputable to talk about some of these things in public than once it might have been. I don’t say it’s easy. It’s certainly contested fiercely.”