Church/state separation means that the church does not bear Caesar’s sword in enforcing the gospel, and that Caesar’s sword is not to be wielded against the free consciences of persons made in the image of God.
Onward p. 142
Moore goes on to give the example of an ax-murder who comes to Christ. While forgiven, that does not mean his sentence is lessened, nor does it mean that while incarcerated, the church should withhold its welcome. More could be said, and certainly there are fine lines to discuss, but that’s not a bad starting point.