Koine

Until the late 19th cent. some considered the Greek of the NT to be a unique, heavenly language. This was thought to be the case because the style of the NT was very different from that found in Greek philosophical texts or in Homer's Iliad and Odyssey. So some concluded that the Greek of the NT was a special "Holy Spirit language" prepared by God to convey his word. This was a maintainable position (although still conjectural) until archeologists began unearthing documents written in a Greek style similar to the NT. And these documents were not concerned with anything official, nor were they meant for public consumption. Rather they were written by everyday, insignificant people about things that were never intended to be handed down through the ages, such as letters and contracts. Even in the language of the Bible, God demonstrates that (in Christ) "he is one of us."

- Peter Enns, Inspiration and Incarnation, pg. 19.