“Death threats are really serious and they need to be taken seriously,” Archbishop Welby said.
“In a time of deep uncertainty, a much smaller amount of petrol is a much more dangerous thing than it was in a time when people were secure. There is a great danger to doing it when we’re already in a very polarised and volatile situation.”
Discussing September's heated House of Commons debate in Mr Johnson was heavily criticised for his comments, Archbishop Welby said a “great deal of really difficult things” were also said by MPs from other parties.
He added: “I think we have become addicted to an abusive and binary approach to political decisions: ‘It’s either this or you’re my total enemy’.
“There have been inflammatory words used on all sides, in parliament and outside - ‘traitor’, ‘fascist’, all kinds of really bad things have been said at the highest level in politics.”
Speaking in the Democratic Republic of Congo, Archbishop Welby called for action to heal divisions across Britain’s “quite broken” society.
The intervention came after police revealed that reports of hate crime had spiked during parliamentary debates around what Mr Johnson labelled a “surrender bill” aiming to prevent a no-deal Brexit.
Some far-right activists threatened to riot at protests over the introduction of the law and called MPs who supported it “traitors”.
The National Police Chiefs’ Council's lead for operations said recent increases in hate crime “seemed to coincide with some of the debates” in parliament, following repeated calls by senior officers for public figures to moderate their language.
“Sometimes the way things are said can be perceived as giving permission to people to act beyond the normal boundaries ... it does have an impact on people,” Chief Constable Charlie Hall told a press briefing earlier this month.
“We know some of that debate is quite strong but we ask people when those debates take place, that they are respectful and mindful of the impact that’s being had on others.”
The combative tone has continued following the passing of the Benn Act and rival calls for a general election or a “final say” referendum to resolve the political stalemate.
Mr Johnson’s description of the law as a “surrender bill” or “surrender act” was repeated by extremists, and high-profile figures including Tommy Robinson have given the prime minister their public support.
On Saturday, Mr Johnson accused parliament of “holding the country hostage” ahead of fresh votes on a potential general election.
Cross-party MPs have reported a dramatic increase in abuse since the EU referendum and several people have been prosecuted for making threats to politicians.
Mr Hall said reports of abuse towards MPs spiked in September and more have been taking up the offer of security advice from the police Parliamentary Liaison and Investigation Team.
Police are also bracing for an increase in protests around 31 October but said there was “no intelligence at the current time” indicating they could be violent.
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