The Archbishop of Canterbury is calling for a cross-party Brexit forum to draw the 'poison' from the debate.
Justin Welby said the Grenfell Tower fire and terror attacks on London and Manchester showed an 'urgent' need for reconciliation between faiths, social groups and generations.
In an article for the Mail on Sunday he contrasted the heroic individual responses to those tragedies with the 'failures of government and a sort of tragic unwillingness to face the realities of divisions and people being left behind'.
Describing how communities pulled together after 'storm of events that have tested our deepest values with an almost unrelenting ferocity', he said the country faced a choice between 'selflessness' of individuals and emergency services and the 'inward looking 'me-first' attitudes' of the government's response.
'We have been severely tested in how we handle diversity, integration, social mobility and inequality. Failure in these areas is ultimately a failure of values.'
Writing in the Mail on Sunday Welby said: 'Exit negotiations will be fierce and the differences on what we should aim for, and how, are very deep. They divide our politicians and our society.
'With a hung parliament, there is an understandable temptation for every difference to become a vote of confidence, a seeking of momentary advantage ahead of the next election.
'For that to happen would be a disaster if our negotiators, faced with the united determination of the EU, go into the room without confidence in their backing in the UK.
'It might turn us inwards and forfeit the opportunity to be a country the world admires and blesses for our generosity and vision.'
Welby said politics was 'rightly hard and tough' but proposed a commission chaired by a senior politician as a forum to achieve consensus.
'Recent events have highlighted the urgent need for a process of internal reconciliation, between regions, social groups, faiths and generations.
'The future of this country is not a zero-sum, winner take all, calculation but must rest on the reconciled common good arrived at through good debate and disagreement.'
Warning decisions over the next two years would impact generations to come, Welby said: 'Our values must be shaped by a recognition of the dignity of every human being, regardless of wealth, status or influence.
'They must be values lived at home so that when we play what I believe can and should be a leading role, it is a role for the good of the poorest of the world.'
But the Archbishop's proposal appeared to fall on deaf ears in the Conservative party with international development secretary Priti Patel rejecting the idea.
'We're pretty clear the vote happened last year and we don't need to have a rerun of the arguments of remain and leave,' she told ITV's Robert Peston.
'The technical details, in terms of how we leave, that work is in train already through David Davis and through his government department, working across the whole of the civil service and obviously our colleagues in Europe, but also with our ambassadors as well.'
But Labour's Yvette Cooper, who suggested a similar cross-party commission after the election, agreed and said Brexit could not be sorted through 'back room deals by a government which has just lost its majority'.
'The Government cannot carry on as usual, pretending that the election didn't happen and that the public didn't deliver their verdict on Theresa May's plan. A Brexit deal - if it is to last - must have a mandate and broad backing behind it, instead of something cobbled together by a small Conservative cabal,' she said.
'Justin Welby is right, now we all have a big job to do in pulling our divided country together - and this could be a start.'
