Sunday is Pentecost, a day many mark as the beginning of the Christian church.

The Book of Acts in the New Testament of the Bible tells the story of a gathering in Jerusalem, not long after the crucifixion of Jesus Christ, where 120 people – including his Apostles, his brothers and his mother – were gathered in a room to celebrate a feast day.

Suddenly, the account says, at about 9 a.m. the group began to hear a whooshing sound from heaven and the Holy Spirit descended upon them. Those gathered saw tongues of fire and soon began to speak other languages, the Bible recounts.

The Apostle Peter who was at the gathering, declared the event to be a fulfillment of an Old Testament prophecy that said the Holy Spirit would “pour out” on believers, both Jews and Gentiles.

Here is the account from Acts of the Apostles Chapter 2, verses 1-6:

“And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Spirit, and began to speak with other languages, as the Spirit gave them utterance. And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven. Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language.”

Here are a few FAQs on Pentecost:

What does the word Pentecost mean? 

It’s derived from a Greek word meaning 50. The first Pentecost happened 50 days after Easter.

What is White Sunday or Whitsun?

White Sunday – or Whitsun – is another name for Pentecost. The term was used particularly in Britain and Ireland and is what Methodists call the day.

Why were the Apostles gathered on that Sunday?

They were celebrating the Feast of Weeks, which was a harvest festival.

Why are pastors wearing red in Church on this Sunday?

Red is the traditional vestment color for Pentecost. Red is also worn on Palm Sunday, Good Friday, all feasts of Our Lord's Passion, and on the feast days of martyrs.

Are there any other special events on Pentecost?

Often churches will hold confirmations and baptisms on Pentecost, honoring the symbolism of the church’s beginning. Confirmation usually involves a teenager making a profession of their faith and becoming a member of their church.

Pope Francis has invited 300 Charismatic and Evangelical leaders to Rome for Pentecost Sunday, the Catholic News Service reported.