Jonathan Chaplin from the Kirby Laing Institute for Christian Ethics has been speaking as the official campaign to keep the UK in the European Union - ahead of a referendum on our membership - has been launched.
Speaking on the News Hour he said there are big issues that need to be dealt with on a united front.
"These challenges are immense and no individual nation states can [tackle] them on their own," he said. "Nor is it enough simply to have ad-hoc co-operation between individual states."
The figurehead of the campaign to stay in, former Marks and Spencer boss Lord Rose, warned of the economic impact of a vote to leave the EU in the referendum promised by Mr Cameron by the end of 2017.
He said: "Those who want us to leave Europe would risk our prosperity, they would, I believe, threaten our safety and they would, I believe, diminish our influence in the world.
"We know our economy would take a hit, what we don't know is how bad that hit would be."
He continued: "They cannot guarantee that jobs would be safe or that prices wouldn't rise.
"They cannot explain how we would stop free movement and simultaneously keep access to the world's largest duty free market.
"They cannot say how our diminished status would impact on our relationships with the US or with China or, indeed, with Commonwealth countries.
"Leaving Europe is a leap into the dark and I don't believe that is a risk that is worth us taking."
But Boris Johnson has claimed the price of Britain quitting the European Union is "lower than it's ever been".
The mayor of London insisted that "in an ideal world" he would want to stay in a reformed EU, but he played down the risks of a so-called Brexit.
The senior Tory repeatedly refused to rule out spearheading the campaign for the UK to leave the EU but insisted he had "great faith" in David Cameron's ability to negotiate better terms of membership.