Birth of the Church
After His blessed Glorious Resurrection, our Lord Jesus Christ appeared to His holy Apostles for forty days to assure them of the Truth of His Glorious Resurrection (Acts 1:3), to comfort them (John 20:20) and to instruct them in the practical preaching and teaching that was difficult for them to comprehend prior to His Glorious Resurrection (John 16:25, Acts 1:3). St. Luke described in his Holy Gospel one of those such teaching session as happened with the Emmaus’ disciples in which He walked with them approximately 7 miles for about 2 hours explaining the Holy Scriptures to them beginning with Moses and the prophets (Luke 24:13-27). In His third apparition at Lake of Galilee, the Lord Jesus Christ spent all night with His disciples to late morning (John 21:4-15).
After His Ascension, the Apostles returned back to the City of Jerusalem with great joy (Luke 24:52) because He ascended to The Father (John 14:28) and He would come back again (Acts 1:11). They stayed in the Upper Room fasting and praying as the Lord directed them while waiting for the descending of the Holy Spirit (Luke 24:49 and Acts 1:4). At that time they chose St. Matthias to take the vacancy left by the betrayer Judas Iscariot (Acts 1:15-26). On the 50th day of the Lord’s Glorious Resurrection (Day of Pentecost) at the third hour (9 am), all the Apostles and the brethren about 120 were gathered together in one accord praying and fasting, when suddenly there came a sound from Heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting. Then there appeared to them divided tongues as of fire and one sat upon each of them and they were all filled with the Holy Spirit and began to speak with other tongues as the Spirit gave them utterance (Acts 2:1-4).
The Day of Pentecost was a great Jewish feast sometimes called Feast of Harvest (Exodus 23:16), Feast of First Fruits (Number 28:26) or Feast of Weeks (Deuteronomy 16:9-10 and Leviticus 23:15). It is called Pentecost because it happens on the 50th day after the Jewish Passover. It began immediately following the Passover by offering the first sheaf of grain and ended by offering two loaves. It was one of the main three Jewish feasts in which every Jew should appear before the Lord (Deuteronomy 16). Josephus mentioned tens of thousands of Jews used to come to Jerusalem to attend this feast and that this was certainly a good opportunity for the Apostles to begin preaching and teaching about the Lord Jesus Christ.
In that day St. Peter stood up and gave his sermon and when the attendants heard his teachings they were cut to the heart and said to St. Peter and the rest of the Apostles what shall we do? Then St. Peter said to them (Repent and let every one of you be baptized in the name of Jesus Christ for the remission of sins. Acts 2:14-36). In that day, three thousand souls were baptized and added to the Church. From that time the Lord began to add to the Church daily those who were being saved (Acts 2:47).