🔼The name Pentecost in the Bible
Pentecost is the Greek name of the feast that is called in the Hebrew Bible: the Feast of Weeks (Exodus 34:22, Deuteronomy 16:10), of Ingathering (Exodus 23:16) or of First Fruits (Numbers 28:26). This festival was to be celebrated seven weeks (or on the fiftieth day) after Pesah or Passover, and was the most significant and festive of the agricultural year.
The historian Josephus wrote that for this feast enormous amounts of Jews trekked to Jerusalem. During times of upheaval, this massive gathering of (mostly armed) Jews caused understandable levels of concern with the Romans.
In the New Testament, the feast now known as Pentecost is significant because on the first Pentecost after the death and resurrection of Jesus, the Holy Spirit was poured out (Acts 2:1). The apostle Paul, who wasn't there at the first Pentecost after Christ's resurrection, acknowledged the importance of the feast. Once he hurried to Jerusalem for it (Acts 20:16) and at least once he celebrated it at Ephesus (1 Corinthians 16:8).
🔼The resurrection of Pentecostalism
Modern Pentecostalism is a Christian movement that emphasizes the working of the Holy Spirit. Although this Pentecostalism is a fairly recent invention (it emerged in the United States in the early 20th century), its prime tenet is as old as Christianity itself and was predated by a movement out of Phrygia: then called the New Prophecy and now mostly referred to Montanism, after main man Montanus, a recent convert with little to no Christian theological training and the unyielding conviction that he was a prophet and was receiving messages from the Holy Spirit.
From roughly 150 AD on, mister Montanus and two accompanying prophetesses named Prisca and Maximilla claimed succession of Philip of Caesarea and his four prophesying daughters, and operated ecstatically in the grip of the Holy Spirit. Montanism proved attractive enough to grow into a massive movement but by that time the church had began to be abducted by people who were much more interested in their own power than in any news from the divine, and ruled him a heretic and Prisca and Maximilla uppity goodies and dangerously reminiscent of the dubious priestesses of pagan traditions.
Montanism took a few centuries to die out and humanity had to wait for more than a millennium until the concrete cast of formality had cracked enough to let some free will and religious spontaneity and originality seep through.
🔼Etymology of the name Pentecost
The name Pentecost is an ordinary Greek word, namely the ordinal number fiftieth:
The name Pentecost literally means Fiftieth and refers to the time passed since Easter, namely seven weeks.