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"...the politics that Christianity requires"?
My first impulse was to suggest "resistance", standing for and with people of good will against Trump and what he represents - the movement of vitriol, revisionism, winning by diminution, exclusion and pandering. And yes there is an urgency because the consequences of Trump are immanent.  
Then I think of the danger of adopting the very weapons of Trump and the trumpists. Is that not the very lesson he inadvertantly warns us of - e.g., "defeating radical Islamic fundamentalism by becoming radical disenchanted/white evangelical/anarchistic/hate-filled/god-wants-me-to-be-rich/exceptionalist USofA fundamentalists? (ps I bet there are fewer radical fundamentalist Muslims than the hard-core, radical fundamentalist USofA'ers who stand with Trump ).  Think of the anarchy that would ensue in a USofTrump.  The only solution would be Stalinism.
Then I return to the question "...the politics that Christianity requires".