Dermot Ahern says the law was designed to "make it virtually impossible for a prosecution to be taken"
It has been confirmed that planning is underway for a referendum to remove the constitutional ban on blasphemy.
The confirmation came as Health Minister Simon Harris said the current ban was "silly" and "a bit embarrassing".
The issue has come back under the spotlight after a criminal inquiry began into comments by Stephen Fry in an Irish interview two years ago.
People convicted of blasphemy under the 2009 Defamation Act can face a fine of up to €25,000.
The minister who introduced the law, Dermot Ahern, said it was designed to be unenforceable.
Speaking to Pat Kenny, he explained: "We made it obligatory on the prosecution to prove intent to hurt, to disabuse a religion - which is something very difficult to prove in a court of law.
"The way in which we drafted it was to allow maximum freedom of expression."
Mr Ahern explained that while there is a constitutional obligation to have an offence of 'blasphemous libel', he did not believe a blasphemy referendum was appropriate at the time.
"The expense that would incur of having a referendum probably [would be] around €2m, at a time when people were losing their wages," he argued.
"Also it would bring out headbangers on both sides of the argument - so in my view it was the last thing the Irish people would have wanted at that particular time. So in effect we decided, rather than propose a referendum, that we would roll over the offence."
He added: "It was carefully crafted in such a way that we would fulfill the constitutional requirement, but on the other hand to make the offence as narrow as impossible - in other words, to make it virtually impossible for a prosecution to be taken."
But Michael Nugent of Atheist Ireland says it should have been dropped.
"The whole thing is absurd anyway - the idea that if the creator of the universe exists it needs Dermot Ahern to protect its feelings is a mockery anyway.
"And the difficultly is with having these theological clauses in our constitutional laws is you never know when somebody's going to decide that their conscious or the creator of the universe is telling them to enforce it, and then it ends up being enforced".
Earlier Minister Harris said he would like to see a referendum on the law being brought forward as soon as possible.
He said: "I'd hope to see it sooner rather than later - this is a democracy, and people have the right to express whatever view they do.
"Stephen Fry, regardless of your own religious views, clearly he was making a number of points that he felt very strongly [about], in his usual witty way. I think we do need a referendum in that regard."
Additional reporting: Jack Quann