During the medieval and dark ages, the Renaissance. Did the Renaissance ever reach there? When did the Greeks start to convert to Christianity compared to Italy and the rest of Europe?
I ask this because I always read about Italy and Northern Europe during those ages while Greece barely gets mentioned after the Roman Empire.
Could you clarify what you are interested in?
Starting under Diocletian, in the IIIrd century, the Roman Empire was divided in two, the Western and the Eastern Roman Empire. Although the Western Roman Empire felled in the Vth century, the Eastern one, also known as the Byzantine Empire, continued until the XVth century when it was overtaken by the Ottoman Empire.
Are you interested in Greece under the Byzantine Empire or under the Ottoman one?
Greece was part of the Eastern Roman Empire, so it didn't really experience the "fall of the Roman Empire"/"Dark Ages" period in ways similar to Western Europe. A quick thumbnail sketch would be that during Western Europe's post-Roman period, Greece was experiencing the Byzantine Empire (which was one of the most sophisticated in history), Neoplatonic philosophy (in the early parts of this period, at least), as well as Iconoclasm and other Eastern/Orthodox movements within Christian history.
Greece Christianized along with the rest of the Roman world, prior to the fall of the Empire in Western Europe. So it doesn't have the Christianization narratives that places like the British Isles, Scandinavia, and Eastern Europe do.