The clumsy quip was made as Thursday night's programme debated David Cameron's troublesome negotiations with fellow European leaders ahead of the planned referendum on Britain's membership of the bloc.
After commenting on how the original European Economic Community was sold to British voters, the man referred to German Chancellor Angela Merkel saying: "She needs telling this about preventing war: their country started the last two".
Watch video of the comments, above.
The man used the topic of the EU to shoehorn a comment about Germany's role in World Wars I and II
Responding to the man, Labour's Lisa Nandy said: "I would just say to the gentlemen there that I really do disagree with you that the EU was established to make war not only unthinkable but materially impossible, and I think on that basis it has done.
"It's right to recognise we need more democratic control in the EU."
Later in the programme, the EU debate was distilled into a discussion about cake, following actor Emma Thompson's comment that Britain was a "cake-filled misery-laden grey old island".
Panelist June Sarpong, spokesperson for the campaign leading the charge for Britain to remain in the EU, said she thought of the UK as a "classic Victoria sponge".
Thursday's 'Question Time' came from Stratford-upon-Avon
Thursday's 'Question Time' came from Stratford-upon-Avon with panelists including Conservative international development secretary Justine Greening, Labour's shadow energy secretary Lisa Nandy, the SNP's John Nicolson.
They were joined by broadcaster June Sarpong and businessman and former Dragon Theo Paphitis.