Just Plain Wrong

Undoubtedly, many people would place all Christians in this category, because of the Emperor Constantine and the state-sponsored oppression he inaugurated [bold mine-DL], leading to the dangerous alliance between church and state continued in European church-state relations down to the present. ~An Evangelical Manifesto

Most of the manifesto is actually pretty unremarkable and even a little dull, to be quite honest, but this single passage reveals such a stunning ignorance of history that something needs to be said.  Constantine, whom we in the Orthodox Church venerate as a saint, did not inaugurate “state-sponsored oppression.”  It is a lie to say that he did, but it is one that you will hear repeated frequently in liberal (and sometimes conservative) Protestant polemics against “Constantinianism” or the “Constantinian Church” as something opposed to the Church of Christ.  Under Constantine, pagan temples were not closed, nor were pagan practices proscribed by law.  Unless you were a recalcitrant Arian or Donatist bishop (or St. Athanasios!), Constantine did not bother with punishing or exiling you.  Two points should be made very clearly: the later model of church-state relations was principally a legacy of Theodosios I and later Byzantine emperors, and this should be balanced by a recognition of just how little oppression there was under most Byzantine emperors.  There were legal disabilities imposed on pagans and heretics, but there was no programmatic persecution or regular use of force against dissenters.  Orthodox effectively received preferential treatment under law, but in practice dissenting Christians were mostly left in peace.  Almost everything people think they know about the “dangerous alliance of church and state” is interpreted through the lens of the Wars of Religion in early modernity, which they mistake as typical or representative of how church-state relations functioned in previous eras.