Why did God choose the day of Pentecost as the day to first pour out His Spirit and begin His New Covenant Church?

The day of Pentecost was one of God's chosen holy days that His people were to present themselves in Jerusalem to offer a sacrifice. Pentecost was also called the “feast of weeks,” or “Shavuot.”

"Three times in a year shall all thy males appear before the LORD thy God in the place which he shall choose; in the feast of unleavened bread, and in the feast of weeks, and in the feast of tabernacles: and they shall not appear before the LORD empty:" - Deuteronomy 16:16 KJV

Because it was Pentecost, there were Jews from all over the world celebrating the holy day.

"And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven." - Acts 2:5 KJV

These Jews that were from other countries spoke the language of the country they were from.

As religious Jews, they would have also spoke Hebrew. Considering that the Roman Empire was in place in that day, the common language throughout the empire was Greek.

Jesus spoke of the promise of the Father – the Holy Ghost - to His disciples. (Luke 24:49, Acts 1:4) It had been foretold by the prophet Joel.

"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 Ghost, and began to speak with other tongues [languages], as the Spirit gave them utterance [the ability]." - Acts 2:1-4 KJV

God has chosen speaking with other tongues as the Spirit gives the utterance [ability] as the sign of a person receiving the baptism of the Holy Ghost.

"And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilaeans? And how hear we every man in our own tongue [language], wherein we were born? ... we do hear them speak in our tongues the wonderful works of God." - Acts 2:7-8, 11 KJV

It is only because God chose this holy day in which Jews from all over the world were present, that they realized this was the miraculous power of God. Otherwise, this great event of the outpouring of His Spirit would have been dismissed as nothing but a group of drunken Galilaeans.

"And they were all amazed, and were in doubt, saying one to another, What meaneth this?  Others mocking said, These men are full of new wine." - Acts 2:12-13 KJV

"But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judaea, and all ye that dwell at Jerusalem, be this known unto you, and hearken to my words: for these are not drunken, as ye suppose, seeing it is but the third hour of the day.

“But this is that which was spoken by the prophet Joel; And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams: and on my servants and on my handmaidens I will pour out in those days of my Spirit; and they shall prophesy:" - Acts 2:14-18 KJV

Peter then preached to them the gospel. By the way, when Peter preached, he was most likely speaking and preaching to his fellow Jews in the Hebrew language, as Hebrew was the language used in their religious lives.

"Now when they heard this [the gospel], they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?

“Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.

“For the promise [the promise of the Father – the Holy Ghost] is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.

“And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation.

“Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.

“And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers…

“And the Lord added to the church daily such as should be saved." - Acts 2:37-42, 47 KJV

To be continued…