What form of Greek was the main language of the New Testament?

Koine Greek was the main language of the New Testament. Koine means “common” and refers to the widespread Greek variety used across the eastern Mediterranean after the conquests of Alexander the Great.

The New Testament books were written in the first century and early second century CE in the broader environment of Koine Greek. The language was used for commerce, administration, literature, and everyday communication across much of the Hellenistic and Roman eastern Mediterranean.

Koine developed from earlier Greek varieties, especially the Attic dialect, but it was not identical to Classical Attic Greek. It had changes in vocabulary, grammar, pronunciation, and style. The Septuagint, the ancient Greek translation of the Hebrew scriptures, also strongly influenced the vocabulary and expression of New Testament Greek.

Some early Christian texts contain Semitic features or Latin loanwords, but the New Testament’s principal language is Koine Greek. Modern Greek is its historical descendant, not the language of the original manuscripts.