Attorney-General Christian Porter says incoming laws on religious discrimination are not designed to protect religious people from blasphemy, rejecting calls for radio host Kyle Sandilands to face sanction for his tirade against the Virgin Mary.

Protesters gathered outside KIIS FM's studios last week to demand the top-rating breakfast DJ be sacked after he said the Virgin Mary "lied" about her so-called immaculate conception.

Kyle Sandilands faced calls for his sacking after he questioned the legitimacy of the immaculate conception. Credit:AAP

"Someone chock-a-blocked her behind the camel shed," Sandilands said. "You might believe everything that's written down 2000 years ago to be absolutely accurate, and good on you - you're dumb, dumb as dog shit."

While debate about the forthcoming Religious Discrimination Act has focused on the rights it gives people of faith, Sandilands' case has drawn attention to parts of the bill which will afford legal protection to speech about religion by non-religious people.