Henri de Lubac:
It is from within that grace seizes nature, and, far from diminishing nature, raises it up, in order to make it serve its (grace’s) own ends. It is from within that faith transforms reason, that the Church influences the state. As the messenger of Christ, the Church is not the guardian of the state; on the contrary she ennobles the state, inspiring it to be a Christian state and thereby more human.
Integralism did not go wrong after Constantine and the Germanic chieftains were converted, bringing their lands and peoples into and under the Church. The problem started with the very act of seeking to convert a people through converting the leader and the elites, and through them to transform society into the City of God. This form of evangelism, if it “succeeds”, leads to the situation of being a Christian leader of a non-Christian people. Because state neutrality with respect to religion is neither possible nor desirable, this leads Christians to attempt to transform society from without, rather than from within.
Attempts to re-Christianize America through evangelizing “the city” (that is, the gentrifying urban elites) will similarly fail, even if they “succeed”. Similarly, attempts to re-Christianize America through the court system are also misguided. Both attempts, whether through cultural power or legal power, are ultimately recapitulations of the Judaizer Heresy, which failed to realize that the power of the Gospel transforms from within, giving each person and society a new heart with the Law written on it, a heart that is capable of love spontaneously, rather than one that requires imposition through law.