The Most Rev Justin Welby renewed calls for a cross-party commission to negotiate Britain's departure from the European Union, as he said major decisions should be taken "off the political table".
The Archbishop, who sits in the House of Lords, told BBC Radio 4's Today programme: "There are literally thousands of separate agreements to come to.
"If each one of those has to be argued as a point of confidence on the floor of the House of Commons, the chance of getting this done in what's now roughly 18 months is infinitesimally small.
"There has to be the political leadership that says we have major questions that are political, huge political decisions - the obvious one is the single market and customs union, but there are thousands of other decisions that can be made.
"Can the politicians not put at the front of their minds the needs of the United Kingdom to come out with a functional, working system for Brexit, and agree that certain things that, as it were, 'off the political table' and will be decided separately in an expert commission, or commission of senior politicians led by someone that is trusted in the political world?"
Meanwhile, Downing Street dismissed the demand for an expert commission and insisted the Government was committed to the two-year Brexit timetable.
The Prime Minister's official spokesman said: "We are committed to, and are, consulting widely on the issues of Brexit but there are no plans in relation to a commission."
