Christians are called to live based on their beliefs. Part of living is to take part in the political process. Politics is the means that Christians have to influence the world. Jesus himself never hesitated to take offense at those who were working against the church. The moneylenders in the temple, pharisees, and others. Christians are called to pray for their enemies but to also act as caretakers for their fellow man and be good stewards of the earth. How can Christians fulfill their purpose if they are turning their backs to the world?
America would still be a colony of England if the founders (primarily religious) had done what is being advocated here. Slavery would still exist in America if not for Christians opposing it. 30 years is the blink of an eye when looked at from the history of Christianity. It's certainly not enough time to judge if Christians should remove themselves from politics.
My reading is that this is exactly how the Christianity evolved from a clandestine, persecuted religion into the dominant religion of the late Roman Empire. Frequently the local Bishop was the only moral man that you could turn to to gain assistance, the local Roman official being either corrupt, disinterested, or a pagan-barbarian carpetbagger. The Church grew as a parallel power-structure of sorts.
The article smacks of liberal emerging church thinking.