Christianity always has been, and always will be, a political religion. We just need to align our definition of political with Scripture:

As God’s Spirit penetrates people’s hearts through the gospel, those people become new creatures (2 Cor. 5:17). They take their faith into every sphere of life, including the workplace, politics, economics, education, and the arts. And in all these realms, they seek to glorify God. They hear Paul’s exhortation in 1 Cor. 10:31, “whether you eat or drink, or whatever you do, do all to the glory of God.” They obey, imperfectly to be sure. But their incipient obedience leads to significant changes in society, as we’ve seen above.

It is true that the New Testament does not focus on the goal of improving the general society. Most of its social teaching concerns relations of love within the body of Christ. But Jesus taught his disciples to minister to people without regard to their creed or national origin (Luke 10:25-37), and Paul, as we saw, urges believers to do good “especially” to the household of faith, but not exclusively there. The early Christians did not have the power to affect much the politics and culture of the Roman empire, but they did what they could. For example, they rescued babies who had been exposed to die and brought them up in their homes.

The Romans, at least, felt threatened. “Kyrios Iesous,” Jesus is Lord, sounded all too much to them like “Kyrios Caesar,” Caesar is Lord, their own fundamental confession. Jesus did not come in his first advent to be an earthly king, but he is indeed King of Kings and Lord of Lords (Rev. 17:14, 19:16), to whom all authority has been given (Matt. 28:18). He is the mighty Son of David, whose kingdom is to stretch “from sea to sea” and “from the River to the ends of the earth” (Ps. 72:8). The Romans persecuted Christians because they believed that Christ’s kingship was a threat to Caesar. The Christians protested that Christ was not an earthly king, and that they sought to be good Roman citizens. They said that sincerely. But in time Christianity overwhelmed the Roman Empire, not by the sword, but by the power of the gospel. In time, Scripture teaches, the kingdoms of this world are to become the kingdom of Christ (Rev. 11:15). So the gospel certainly is a political movement. That is not to say that Christians should seek political power by the sword. But they should never imagine that their faith is politically irrelevant.

-John M. Frame, “In Defense of Christian Activism“