Speaking on the place of faith in the public square, during the last in a series of Westminster Faith Debates on Tuesday, organised by Lancaster University in partnership with Theos, Dr Williams appealed for less panic among religious people who were engaged in debate.
Refusing to try to "be God", and acknowledging that one might fail, was "a recognition of the majesty and supremacy of the God you believe in. . . I think he can look after himself!"
An argument might be advanced from a religious conviction, Dr Williams said, but "if I can only appeal to my faith in public discussion, it's not going to make very much impact. I have to look for other areas of convergence."
There was, he suggested, a theological reason for this: "If I believe that assisted dying, or gambling . . . are not in accord with God's will for human beings, of course there will be pragmatic arguments against them, because they are not going to work."
He saw, he said, the extent to which people of faith felt "victimised or marginalised", but was not sure that they always saw it clearly. A few "extremely hard cases" had created a "slightly highly coloured view of where we are".
Dr Williams agreed, however, with a contribution made by Cardinal Cormac Murphy-O'Connor, the Archbishop Emeritus of Westminster, who described the dangers of "militant relativism".
One of his "biggest worries" was moving into a climate "where people seem to assume we all know what's rational, but unfortunately a few religious people seem to complicate matters".
It was important to remind people that the language of human rights had religious roots, and "depends on a really big act of faith in human dignity".
Tony Blair, also present at the event, agreed that this "basic and fundamental" truth was a "huge contribution" that people of faith could make to society. The former Prime Minister, the target of a protest outside the venue of the debate, Methodist Central Hall, spoke openly about his own faith.
He believed in "salvation through Jesus Christ", and had prayed on his knees with the Salvation Army while he was leader of the Opposition - although he had not done so, as had been suggested, with President George Bush.
Mr Blair said that he wanted to see "religion-friendly democracy and democracy-friendly religion".
While it was "completely justifiable" for people to advance an argument as a result of religious conviction, democracy was "pluralistic", and people must accept that the views of others were equally valid.
It was particularly important to model this at the moment, he said, because people in the Middle East, while moving towards democratic systems, needed to understand the "proper place" of religion.
Dr Williams took the opportunity to promote the outreach, presence, and communication of churches "on the ground".
He gave as an example Coleford, in Gloucestershire, where the vicar had organised a book of condolence, and clergy had gone into schools, after three children were stabbed to death last week.
"The church is where people want to put . . . a lot of their otherwise unmanaged feeling and suffering."
On the question of women bishops, Dr Williams said that he had recently learned "just how difficult it is for women to hear an all-male body pronouncing on their future".
While he still thought that the bishops had the right general idea, that was "not going to make much difference to those who heard it as offensive and problematic. . .We expect people to be able to say what they are feeling about issues, as well as what they are thinking, and to be heard and be taken seriously."
While the dialogue remained good-natured for the most part, Dr Williams did tell Mr Blair that he remained unconvinced that the Labour Government's plan to "regenerate an impoverished area of Manchester by importing a super casino" was "utterly, utterly bizarre".