The Dark Ages were so characterized by those who studied such things after the Dark Ages. A significant discernible feature between the times was the advent of the printing press and the Gutenberg Bible. The Reformation in great part discerns that period of time wherein the laity was denied access to Scripture, the Word of God, unless passed via the Catholic Church.
The title of Christian is not limited to those who are members of the Roman Catholic Church, but is discerned by the Holy Spirit for any who have faith in Him. Accordingly, the Dark Ages, were noted by the Reformers as specifically being a period within the Church Age where Christians (saints, believers, those with a relationship with God through Christ Jesus) were not allowed to have a relationship with Him by those from the Roman Catholic Church insofar as they could control events,...unless the saint followed the man-made rules of the church.
Accordingly, the Dark Ages were quite characterized by persecution of Christians. Perhaps at the hands of other Christians, perhaps in a confused state where 'protestants'(I use the term loosely to refer to saints not belonging to the Roman Catholic Church, but nonetheless had a believing relationship with God, whereas the term protestant refers more closely to Luther's edict nailed to the cathedral doors and the following century of secular development.) and atheists and agnostics may have fallen to physical malevolence from the Church, but primarily an emphasis existed where those who are seeking a righteous relationship with God were typically denied opportunities at the hands of fellow Christians.
It is generally more enlightening to study history from the point of view of those who made the history, while maintaining a wherewithal made easy from knowledge of concurrent and later events. The Dark Ages are a time of enormous historical expose, but rarely manifest by those who view the period as agnostic or atheist history.
Significance of Berkeley's noiseless tree or even the Cartesian, "Cogito ergo sum" take on considerable significance when compared to the previously accepted 'paradigms'.
How would a gnostic view these historical advents in comparison and their possible impact of history? Interestingly, Scripture has remained true throughout the millenia, and yet is still considered a threat by those who fail to seek a righteous relationship with God.