This Sunday will mark the Christian festival of Pentecost. What does it mean and why is it celebrated?

Last Sunday marked Ascension Sunday, when Christ ended his earthly ministry and ascended to heaven, leaving his disciples and sitting at the right hand of his Father. Pentecost is the subsequent landmark in the Christian calendar, and marks the pouring of the Holy Spirit, the third person of the triune Godhead, on Jesus' disciples.

Pentecost is the Greek name for the Jewish harvest festival of Shavuot, also known as the Feast of Weeks, coming 50 days after Passover.

The event that inspired the Christian celebration is narrated in the book of Acts:

'When the day of Pentecost had come, they were all together in one place. Suddenly from heaven there came a sound like the rush of a violent wind, and it filled the entire house where they were sitting. Divided tongues, as of fire, appeared among them, and a tongue rested on each of them. All of them were filled with the Holy Spirit and began to speak in other languages, as the Spirit gave them ability'(Acts 2:1-4).

A bewildered crowd then wonders how they are suddenly hearing the disciples in their own native languages, though some in the crowd 'made fun of them and said, "They have had too much wine."'

An emboldened Peter then steps up to tell the crowd that they are not in fact drunk, since it's only nine in the morning. The event he says, is in fact a fulfilment of the prophecy of Joel, which declared that 'In the last days, God says, I will pour out my Spirit on all people. Your sons and daughters will prophesy, your young men will see visions, your old men will dream dreams. Even on my servants, both men and women, I will pour out my Spirit in those days, and they will prophesy' (Joel 2:28-29). 

The event effectively marks the birth of the early church, and marks out the special place of God's Spirit in the life of believers, enabling miraculous speech, wonders and an inspired public witness. It fulfils Christ's promise of a 'comforter' to come and sustain and sanctify Christians for their lives after his departure from earth.

In the UK Pentecost has also been known as Whitsun, or White Sunday, while the ecclesial imagery for the occasion often uses red banners, robes or images of fire to represent the fire of the Holy Spirit.

Pentecostalism is a more recent, 20th century church movement which finds its charismatic roots in the story of Pentecost, emphasising the importance of a direct, dramatic experience or 'baptism' of the Holy Spirit, as in Acts.

As in previous years, Pentecost will this year will tie in with the culmination of Thy Kingdom Come, a global prayer initiative led by the archbishop of Canterbury Justin Welby, inviting Christians to pray for their friends to become believers.