MALCOLM Turnbull is akin to the unfortunate chap whose job it was to walk behind a Roman emperor mid-triumph with the repeated reminder: “You are mortal.”

The role is called “memento mori” and it is a difficult one because one slip and the emperor will consider you an enemy and dispatch you, possibly to the certain political death of the Defence portfolio.

But Mr Turnbull trod that fine line last night, risking the wrath of Prime Minister as he urged a calmer line towards the threat of the Islamic State.

He did not criticise Tony Abbott but clearly sees danger in the PM’s “they’re coming for us” line.

The Communications Minister linstead warned against overreacting to threats from the brutal Mideast extremists, saying it would only encourage them.

He urged against comments which make us “amplifiers of their wickedness and significance”.

This is in contrast to the Prime Minister’s dramatic depiction of the IS claims to be spreading terrorism to western nations, and to concerns raised after attacks in Europe and Tunisia and the Sydney cafe siege.

Mr Turnbull used a speech to make a wideranging review the rule of law and the tone of debates but his most striking remarks related to the discussion of national security matters.

He told the Sydney Institute IS was not “Hitler’s Germany, Tojo’s Japan or Stalin’s Russia”.

“Its leaders dream that they, like the Arab armies of the seventh and eighth century, will sweep across the Middle East into Europe itself,” Mr Turnbull said in his speech.

“They predict that before long they will be stabling their horses in the Vatican. Well, Idi Amin wasn’t the King of Scotland either.

“We should be careful not to say or do things which can be seen to add credibility to those delusions.”

While also cautioning against understating the IS terrorist menace Mr Turnbull criticised those who attacked others for not being tough enough on national security.

Mr Turnbull said a national debate should be conducted in “in a considered manner respectful of the views and experience of others”.

He said accusing those who opposed national terrorist measures as pro-terrorist was as stupid as denouncing supporters as proto-fascists.

Last month Mr Turnbull was among cabinet ministers who questioned plans backed by MrAbbott and Immigration Minister Peter Dutton to remove the citizenship of those linked to terrorism, even if they were Australian born and had no other nationality.

He applauded the retreat on the proposal and the replacement legislation.

“The rule of law is respected because a person whose citizenship ceases in those circumstances has full recourse to the Australian courts under the constitution to contest the matter on its merits,” he said.