When Jesus was asked, "what is the greatest commandment?" He replied, "love God with all your heart, soul and mind. And the second is, love your neighbor as yourself."
From that, I take the following. God commands us to: (1) love God, and (2) love people. Policy is effectuated in the U.S. through politics. Policy affects people, either for good or for bad. Thus, being active politically permits me to have a role in promoting policies that are good for people. So being politically active is one way that I can love people.
Being politically active, AND doing it constructively. That is my responsibility.