'''Koine Greek''' is the popular form of Greek which emerged in post-Classical antiquity (c.300 BC – AD 300), and marks the third period in the history of the Greek language. Other names are ''Alexandrian'', ''Hellenistic'', ''Common'', or ''New Testament'' Greek. Koine is important not only to the history of the Greek people, for being their first common dialect and main ancestor of modern Greek but also for its impact on the [[Orthodox Church]] and the rest of the world. It was the original language of the [[New Testament]] of the [[Bible]] as well as the medium for the teaching and spreading of [[Christianity]]—''unofficially the second language of the [[Roman Empire]]''.
Biblical Koine refers to the varieties of Koine Greek used in the Bible and its related texts. It is useful in the complete education of an Orthodox christian. Its main sources are: