Article: Most Greeks are Christians, belonging to the Greek Orthodox Church. During the first centuries after Jesus Christ, the New Testament was originally written in Koine Greek, which remains the liturgical language of the Greek Orthodox Church, and most of the early Christians and Church Fathers were Greek-speaking. There are small groups of ethnic Greeks adhering to other Christian denominations like Greek Catholics, Greek Evangelicals, Pentecostals, and groups adhering to other religions including Romaniot and Sephardic Jews and Greek Muslims. About 2,000 Greeks are members of Hellenic Polytheistic Reconstructionism congregations.

Now answer this question: This language is the official dialect of worship for the traditional sect for church worshipers of Greece ?
Koine Greek, which remains the liturgical language of the Greek Orthodox Church