Identity politics is much more than the politics of religion, gender or ethnicity. In terms of what has been happening in the United States and in Europe it could be described as the uprising of the working class (blue-collar workers, in the US) against a rich liberal elite.
The people who backed Trump were the blue collar workers who have seen their manufacturing jobs disappear overseas and nothing fill the gap and seen more and more immigrants come into the country to compete for the poorly paid jobs left for them driving wages still lower. When you have large groups of threatened insecure economically deprived people like this they tend to break up into small special interest groups; fundamentalist religious groups, anti-immigrant groups; extreme right wing political groups. They all seek simple solutions to complex questions.
What was so clever of Trump was to see that there were an awful lot of special interest groups, groups feeling downtrodden under the current system - and he exploited them. To the underpaid and unemployed was 'gonna bring manufacturing back to America, penalise companies opening plants in other countries.' To the anti-immigrant groups he was 'gonna stop all those illegal immigrants coming in and taking 'your' jobs, he would build a wall along the Mexico/US border. To the fundamentalist christians he said he was, gonna send all the muslims home and not let anymore in'.
Do not deceive yourselves, the same politics of identity is developing in the UK and in Europe. The rise of anti-immigrant groups, ethnic groups developing a ghetto mentality to protect themselves. UKIP is the Trump of the UK. They are appealing to those who have lost most economically. Those in the zero hour/gig economy with uncertain employment, and poor pay, who see themselves as being made poorer by the number of immigrants in this country.
Take the Stoke by-election. UKIP If elected, has promised to “make Britain great again”. Money from the foreign aid budget would go to the NHS. They would have a “firm but fair” immigration policy, would put “British people first” and pledged to put locals “at the top of the queue for housing”. Not really that different to what Trump said in the run-up to his election.