* UK PM Johnson criticised for Brexit language
* Aide Cummings tells opponents to deliver Brexit
* No pressure, we're enjoying it: Cummings
* EU's Barnier says no-deal exit would be UK's fault
By Kate Holton
LONDON, Sept 27 (Reuters) - Prime Minister Boris Johnson's most senior adviser has said British politicians should not be surprised by the mounting anger over Brexit and said the atmosphere will get ever more toxic unless the result of the referendum is delivered.
Parliament, locked in a three-year battle over how, if or when the country should leave the European Union, reached boiling point on Wednesday when Johnson and his opponents spent hours hurling allegations of betrayal and deceit across the chamber of the House of Commons.
Opposition lawmakers accused Johnson of stoking hatred and cast him as a cheating dictator. One called him a liar. Johnson dismissed death threats against female law-makers as "humbug" and accused his opponents of "surrender" to European leaders.
Britain's leading bishops said on Friday this behaviour must stop.
But Dominic Cummings, adviser to the prime minister and mastermind of the 2016 campaign to leave the EU, said lawmakers seeking to thwart Brexit should not be surprised by the reception they receive around the country.
"If you are a bunch of politicians and you say that we swear we are going to respect the result of a democratic vote and after you lose you say 'we don't want to respect that vote'. What do you expect will happen?" Cummings said at a book launch on Thursday night, reported by the Daily Telegraph.
"I find it very odd that these characters are complaining that people are unhappy about their behaviour now."
Johnson, the public face of the Vote Leave campaign, has also said that tempers need to calm down and that resolving Brexit would "lance the boil".
The Conservative Party elected him as leader in July on his promise to break the impasse and take Britain out of the bloc by Oct. 31.
But he has faced defeat at every turn, losing his parliamentary majority, every vote in the legislature, and a groundbreaking case in the Supreme Court over his decision to suspend the assembly.
Three years since Britons voted to leave the EU, the outcome remains mired in uncertainty with possible outcomes ranging from a departure with a new divorce deal, a no-deal exit, a second referendum, or no Brexit at all.
Cummings rejected a suggestion that the government would back a "soft Brexit" - one that keeps Britain more closely aligned to EU rules - in order to get a deal by Johnson's October deadline.