In his conference speech, the Prime Minister responded to the Labour leader's "anti-business" attack on the energy giants by stressing how he was behind big business, which created jobs and prosperity; profit, the Tory leader insisted, was "not a dirty word".
He made clear he wanted to do more than simply "clear up the mess" left by the previous Labour Government, declaring: "Let us pledge today that we will build something better: a land of opportunity. A country built on that enduring principle, seared in our hearts, that if you work hard, save, play by the rules and do your fair share, then nothing should stand in your way."
And the PM insisted his vision was a meritocratic one. "It makes no difference," he explained, "whether you live in the north or in the south, whether you're black or you're white, a man or a woman, the school you went to, the background you have, who your parents were. What matters is the effort you put in, and if you put the effort in you'll have the chance to make it. That's what the land of opportunity means. That's what finishing the job means."
On fixing the economy, he warned that while the country was turning a corner, "we are not there yet; not by a long run".
He referred to "Red Ed" and argued that Labour's economic strategy amounted to "more spending, more borrowing, more debt", insisting: "To abandon deficit reduction now would throw away all the progress we have made."
Mr Cameron made clear the Tory 2015 manifesto would include measures to prevent young people claiming unemployment benefits after leaving school or college, saying that every under-25 should be "earning or learning".
And he signalled an intention to reduce taxes, telling activists: "We're Tories. We believe in low taxes. And believe me, we will keep on cutting the taxes of hard-working people."
But Mr Cameron also warned of more austerity following the election, even if the recent return to growth was sustained, insisting the Tories would stick to their economic course "until we've paid off all of Labour's deficit, not just some of it" and would run a surplus - spending less than they would take in from tax and other revenues - even after the deficit was eliminated.
On Scottish independence, he said: "The date of the referendum has been set. The decision is for Scotland to make. All the arguments about our economy, jobs, currency ... make an unanswerable case for the UK.
"But I want a more simple message to go out to all the people of Scotland ... From me, from this party, from this country, from England, Wales, Northern Ireland - we want you to stay; we want us to stick together."
Insisting the removal of welfare from 18 to 25-year-olds was not "callous", he explained that, just like parents, the Government would "nag, push, guide and do anything" to see young people get ahead. He added: "So this is what we want to see: everyone under 25 earning or learning."
After his 49-minute speech, he was joined on stage by wife Samantha as the audience gave him a standing ovation. The pair left the auditorium to the sound of Fleetwood Mac's Don't Stop (Thinking About Tomorrow), used by Democrat Bill Clinton as the soundtrack to his successful 1992 campaign for the US presidency.
In response to the speech, Mr Miliband tweeted: "David Cameron's speech shows he does not know where to start in tackling the cost of living crisis facing Britain's hard-working families. The last thing families want is him to 'finish the job' when prices have risen faster than wages and average pay is down by almost £1500."