Pentecost Sunday marks the day when the Holy Spirit descended upon the Apostles. Pentecost means 50, 5 to the 10th power Pentecost Sunday occurs 50 days after Easter.It is the 7th Sunday after Easter. The Pentecostal movement derives its name from the New Testament event in Acts 2. Acts 2:1 When the Day of Pentecost had fully come, they were all with one accord in one place. 2 And suddenly there came a sound from heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting. Pentecost Sunday marks the day when the Holy Spirit descended upon the Apostles. Acts 2:3 Then there appeared to them divided tongues, as of fire, and one sat upon each of them.4 And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit gave them utterance. 6.Pentecost comes 10 days after the Ascension of Jesus Christ. Acts 1:9 Now when He had spoken these things, while they watched, He was taken up, and a cloud received Him out of their sight. 10 And while they looked steadfastly toward heaven as He went up, behold, two men stood by them in white apparel,11 who also said, “Men of Galilee, why do you stand gazing up into heaven? This same Jesus, who was taken up from you into heaven, will so come in like manner as you saw Him go into heaven.” Pentecost is also known as “the birthday of the Church.” Acts 2:47 praising God and having favor with all the people. And the Lord added to the church daily those who were being saved. Pentecost fulfills Jesus' promise to send the “Counselor” and "Spirit of Truth" in John 16:5-15 John 16:5-15 “But now I go away to Him who sent Me, and none of you asks Me, ‘Where are You going?’ 6 “But because I have said these things to you, sorrow has filled your heart. 7 “Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you. 8 “And when He has come, He will convict the world of sin, and of righteousness, and of judgment:9 “of sin, because they do not believe in Me; 10 “of righteousness, because I go to My Father and you see Me no more; 11 “of judgment, because the ruler of this world is judged. 12 “I still have many things to say to you, but you cannot bear them now. 13 “However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. 14 “He will glorify Me, for He will take of what is Mine and declare it to you. 15 “All things that the Father has are Mine. Therefore I said that He will take of Mine and declare it to you. Pentecost launches the large-scale spreading of the Gospel after Jesus' ascension. Acts 2:41 Then those who gladly received his word were baptized; and that day about three thousand souls were added to them. After Peter spoke to the crowd after receiving the Holy Spirit, some 3,000 people were baptized. 10.Jews also celebrate Pentecost, but not for the same reason as Christians. 11.The celebration by Jews of Pentecost is to observe God giving the Ten Commandments on Mount Sinai 50 days after the Exodus.