The alliance between the church and the state [at the time of Constantine] brought a measure of prosperity and prestige, but it hardly enhanced the spiritual stature or strengthened the moral fiber of the Christian community. With thousands embracing the faith there seemed little need for missionary effort. Individual conversion and personal commitment were no longer matters of great concern. Converts entering the church brought with them their paganism as well as their patrimony. From Constantine to the present time the Christian church in the West, Protestant as well as Roman Catholic, has at different times and in varying degrees been identified with and supported by the state. Ecclesiastical power has been wedded to political power to the detriment of spiritual power.
(J. Herbert Kane. A Concise History of the Christian World Mission. Grand Rapids, MI: Baker Books. 1978, 1982. 34.)
Jesus said to them, “Render to Caesar the things that are Caesar’s, and to God the things that are God’s.” (Mark 12:17a ESV)
I don’t think that Jesus ever intended for the church to be mixed up in political power. Yes, we are to be obedient to those in leadership over us, but I don’t think that that means that the state should run and protect the church or that the church should run the state. We need to learn that when “Ecclesiastical power has been wedded to political power” that it is “to the detriment of spiritual power.
Think about the early Christians. “Many signs and wonders were regularly done among the people” (Acts 5:12a ESV), but the “unchurched” people; the worldly people; the non-Christians would not dare join them. In the early days of the church, you would not have had converts to the faith bringing “with them their paganism as well as their patrimony.” The church was “clothed with power from on high” (Luke 24:49 ESV), not power from the government. There’s a big difference.