Jeremy Corbyn is "admirable" for sticking to his pacifist beliefs, but by doing so he shows that he is "unfit to be Prime Minister", a Tory MP said as Parliament prepares to vote on military action in Syria.
His comments come as MPs prepared to caste their vote on Wednesday as to whether to authorise airstrikes in Syria.
Rees-Mogg said: "I admire the courage of pacifists.
"I admire the courage of people who were conscientious objectors in the First World War and it goes against the grain of the nation as a whole but if that is what you profoundly believe actually it is a very brave thing to put forward, so I admire Jeremy Corbyn for doing that.
"I am afraid it also makes him unfit to be Prime Minister because there is always the risk of the Prime Minister may have to go to war and you cannot have a Prime Minister who will not go to war."
Although Rees-Mogg admitted that Bashar al-Assad was "unquestionably an evil man", he said that there are "no easy answers" in Syria.
His comments came after Jones said that most civilians in Syria were killed by the Assad regime, rather than Islamic State
Rees-Mogg replied: "Assad is unquestionably an evil man, but regrettably our efforts to enforce regime change in other countries have made things worse rather than better.
He continued: "There are no easy answers in this situation.
"I think a lot of mistakes were made earlier on... what is the best way of getting stability in Syria? Well probably first of all its's to get rid of Isis.
"I think it is highly questionable whether there are other forces within Syria who are ready to take over in the absence of Assad and therefore you probably are dealing with Assad - particularly if he has the support of Russia."
Jones's interview with Rees-Mogg touched on a number of issues, including gay marriage. The Tory MP maintains that he does not support homosexuals getting married because of his Catholic faith.
Following the interview, Jones was drawn into a Twitter feud over the issue of Syria with journalist Hugo Rifkind.
@hugorifkind Of course Saddam Hussein was a terrorist? He employed state terrorism on grand scale (for a long time with Western complicity)— Owen Jones (@OwenJones84) December 2, 2015
@hugorifkind um, sorry for the tiredness. but your point wasn't/isn't exactly clear. and Saddam was a terrorist and ISIS are a regime.— Owen Jones (@OwenJones84) December 2, 2015
@hugorifkind But most Syrians are being killed by the Syrian state, not 'stateless chaos', so again, I'm at a loss.— Owen Jones (@OwenJones84) December 2, 2015
@hugorifkind I'm obviously not suggesting the West does that. I'm confused here so I'll just step out again.— Owen Jones (@OwenJones84) December 2, 2015