- Video report by ITV News Political Correspondent Libby Wiener
Philip Hammond says it is a "delusion" to think the EU will renegotiate a better Brexit deal than the one Theresa May has agreed.
The Chancellor, opening the third day of debate on the Withdrawal Agreement, said: "I have observed this process at close quarters for two-and-a-half years and I'm absolutely clear about one thing - this deal is the best deal to exit the EU that is available or that is going to be available.
"The idea that there's an option of renegotiating at the 11th hour is simply a delusion.
"We need to be honest with ourselves - the alternatives to this deal are no deal or no Brexit."
- Watch the debate in full
Mr Hammond added that leaving without a deal or having no Brexit at all would have a negative impact on the country.
"Either will leave us a fractured society and a divided nation.
"Only the compromise of this negotiated deal - delivering on the referendum result by leaving the EU, ending free movement of people and reasserting our sovereign control over our laws while at the same time maintaining the closest possible trade, security and cultural links with the European Union to protect our jobs, our living standards and our values - can allow our country to move on.
"Only that compromise can bring us back together after Brexit is delivered, and we should remember the lesson of history - that divided nations are not successful nations."
Time is running out for the prime minister to convince MPs to back her deal in a crucial vote scheduled for December 11.
- While the Chancellor has said that the idea of getting a better Brexit deal is "delusional", many in Westminster believe that getting it through the Commons is also delusional, ITV News Polticial Correspondent Libby Wiener reports.
Mr Hammond also pointed the Bank of England's warnings over the economic impact of a no deal Brexit and agreeing to Mrs May's plan would at least end uncertainty.
He said: "This House has before it a deal which can deliver the certainty which will unlock the potential of our economy, that will assure Britain of the brighter future it craves.
"So let us not be the generation who will have to explain to our children and our grandchildren why we let that opportunity slip from our grasp.
"Let's choose now to move on to that brighter future, not to go back to square one with continuing uncertainty, division and disharmony."
A sombre John McDonnell responded to Mr Hammond by saying he had four key points he wished to stress.
The Shadow Chancellor said a no deal Brexit should be avoided, before adding that Mrs May's deal was not an acceptable one.
Mr McDonnell says Labour will uphold the result of the referendum with the aim of securing jobs as part of any deal they could negotiate. He also insisted there should be some focus on the impact on communities.
He said: "I give this assurance that Labour will not countenance a no deal and will work assiduously to avoid it.
"But let me also say the Government threatening MPs with the prospect of a no-deal Brexit to engender support for its own deal serves only to reveal a desperation in Government and it's proving to be completely counterproductive."
Tory veteran Sir Nicholas Soames said he was backing the Prime Minister but her position would be "very difficult" after a heavy defeat on December 11.
Conservative MP Johnny Mercer said he had previously "avoided the subject like the plague" and had always been "ambivalent" about the process of leaving the EU.
He said: "And it has brought out, I'm afraid to say, a side in a lot of my friends and colleagues who I love dearly that I have not particularly enjoyed.
"But I've been forced to have a view today and I'll be honest."
Speaking in the Commons, he said: "I came here because I couldn't watch my country have a politics dominated by a political class out of touch with the nation they govern."
Explaining why he was not backing the Prime Minister's deal, Mr Mercer said it "indicates what I have long feared - that too many in Government have failed to grasp why people voted to leave the European Union in the first place".
DUP MP Ian Paisley Jr included Nazi appeasement in a comparison with the EU as he urged the Conservatives to go back to the drawing board on their Brexit deal.
He said: "Some of the huge issues that have driven our nation - whether it's been the corn laws, imperial preference in the 19th century, the appeasement of the Nazis in the 1930s and our relationship with the EU or the EEC in the 1960s - all of those matters were about divisions in the Conservative Party.
"It is not about how this side of the House is going to vote on the 11th of December that actually matters but what that side of the House is going to do.
"They have a choice - to stuff Northern Ireland into some adjunct of this kingdom and damage this kingdom forever and for generations, or else they can say there is a better way, there is an alternative and we will find it."
Former Brexit secretary David Davis admitted there would be "hiccups" along the way but said they were a price worth paying.
"It was me that actually negotiated the implementation period element of this and for that reason, precisely because it's not without hiccups, it's not without issues," Mr Davis explained.
"There will be practical issues in the first year of a WTO outcome.
"But that does not overwhelm the big advantages, the massive advantages, that having the freedom to negotiate our trade deals would give us."
Outside of the chamber, Eastbourne MP Stephen Lloyd announced that he had resigned the Liberal Democrat whip over Brexit.
A Liberal Democrat spokesman said: "We respect what we know was a difficult decision for Stephen ahead of next week's vote and are sorry to see him go. Liberal Democrats are clear that we will be voting against Theresa May's deal.
"The Liberal Democrats have campaigned for an exit from Brexit and a People's Vote where people can choose to remain in the European Union since the referendum was held.
"We will continue to fight for this in Parliament."