The Secret Old Testament Backstory of Pentecost

Jun 06, 2025

Pentecost is upon us!

We all know the incredible story of our Church’s birthday - the great wind of the Holy Spirit filling the house, flames appearing above the disciples’ heads, and the gift of tongues allowing them to be understood by people of every nation.

But what many people don’t know is that, like so many other things in the New Testament, Pentecost didn’t just come out of nowhere.

It's actually connected deeply to the Old Testament and was originally a Jewish feast.

In fact, the word "Pentecost" means "fifty" in Greek, and it was celebrated 50 days after Passover. 

In particular, it was one of the three pilgrim feasts that required Jewish men to make a trip to Jerusalem. Sometimes called the Feast of Weeks, it was a harvest festival that foreshadowed what we now celebrate this Sunday.

How, you ask?

Well, the Feast of Pentecost was a celebration commemorating when the people of Israel became the people of God.

Recall that Moses led the Israelites out of slavery in Egypt, crossed the Red Sea and ended up at the foot of Mt Sinai. And about 50 days later, they swore a sacred covenant oath with the Lord that he would be their God and they would be his people.

And of course, following the covenant ceremony they received the 10 Commandments through Moses, the Law of the Covenant. 

But before all of that, when the Israelites first arrive at Sinai, God tells Moses on the mountain that the people should ritually purify themselves, because he’s coming in three days. And he does:

On the morning of the third day there were thunders and lightnings, and a thick cloud upon the mountain, and a very loud trumpet blast, so that all the people who were in the camp trembledThen Moses brought the people out of the camp to meet God; and they took their stand at the foot of the mountain. And Mount Sinai was wrapped in smoke, because the Lord descended upon it in fire; and the smoke of it went up like the smoke of a kiln, and the whole mountain quaked greatly. And as the sound of the trumpet grew louder and louder, Moses spoke, and God answered him in thunder. And the Lord came down upon Mount Sinai, to the top of the mountain; and the Lord called Moses to the top of the mountain, and Moses went up" (Exodus 19:16-20)

Did you hear that? God descended upon the mountain in fire!

So God came down from heaven in a very visible way. And yet - none of the Israelites set foot on the mountain. Why? Because they hadn’t obeyed God's command. They hadn't purified themselves as God had asked. Only Moses and Aaron went up, and God communicated the 10 Commandments. 

So what are the parallels between the scene at Sinai and Jerusalem in Acts 2?

First of all, both take place on mountains. Mt Sinai is the scene of the first. Pentecost takes place on Mt. Zion in Jerusalem.

Both events have dramatic weather patterns: Sinai has thunder and lightning, smoke and fire, and an earthquake. Again, the Lord actually descends in fire in Exodus 19:16 and appears like a “devouring fire” on top of the mountain in Exodus 24:17. 

A point of interest here is that the word “thunder” as used in the book of Exodus can be translated as “voices” – “qol” in Hebrew. So it is the sound of voices, or the voice of God, they hear on the mountain.

And we're not talking library voices here. 

In fact, "qol" is the same word used to describe the sound made when God descends into the Garden of Eden after the original sin of Adam and Eve. Again, it’s not just any old voice.

In Psalm 29, the “qol” or voice of the Lord,  “breaks the cedars…flashes forth flames of fire…shakes the wilderness…makes the oaks to whirl and strips the forests bare.”

In other words, the thunder or voice of the Lord is intense!

Sounds similar to what's going on in Acts 2 with the rushing wind, doesn't it?

And think about this…what do the people in Jerusalem hear? The voices of the Apostles proclaiming the glory of the Lord in different languages after the tongues of fire descend upon them reminiscent of the descending of fire in Exodus 19.

What other connections are there between these two stories?

At Sinai the people were kept away from the fire on the mountain because they had not purified themselves.

But at Pentecost in Acts, the fire comes into their midst through the Apostles. They don't have to fear this time, especially since Christ has fulfilled the terms of the blood covenant they broke at Sinai (and all the other covenants of the Old Testament). The curse of death has been lifted.

At Sinai the Israelites received a law written on stone – the Ten Commandment.

At Pentecost the people received a law written on the human heart. The prophet Jeremiah said, "Behold, the days are coming, says the Lord, when I will make a new covenant...not like the covenant I made with their fathers when I took them by the hand to bring them out of the land of Egypt...But this is the covenant which I will make with the house of Israel after those days, says the Lord: I will put my law within them, and I will write it upon their hearts."

St. Thomas Aquinas says that the law of the New Covenant is nothing other than the grace of the Holy Spirit, which is exactly what showed up at Pentecost.

How about one more parallel, which is perhaps the most powerful?

Upon their arrival at Sinai, the Lord tells the Israelites he will swear a covenant with them and they will be his people if they follow the commands he has given them. So they receive the law of the covenant and agree to it. All the people reply, “All that the Lord has spoken we will do.”

Then comes a covenant oath ceremony where Moses sacrifices two oxen and sprinkles half of the blood on the altar and half of the blood on the people. 

This is a very serious ceremony that often accompanied the swearing of covenants. The sacrificial animal symbolized what would happen if someone broke the covenant. Put simply, you would die like that animal if you broke the covenant oath.

Through this ceremony, the people had to declare their fidelity and then show they meant it through sacrifice. Again, the penalty for breaking a covenant was death. Everybody understood this.

Moses then goes back up Sinai into the fire of God on the mountain...and we all know what happens.

The people lose heart thinking Moses has been consumed by God and they have Aaron construct a golden calf to worship...and commit terrible sexual sin around it. (The Golden Calf was Apis, a bull god of fertility they worshipped in Egypt. In Exodus 32:6 we read they "rose up to play" around the idol, which is a sexual euphemism.)

So basically, 40 days after they swear a blood oath to God under the penalty of death, they break it.

Moses comes down the mountain, sees what’s going on, smashes the stone tablets and cries out, “Who is on the Lord’s side?” His kinsmen, the Levites, come to his side, and he says, "slay the idolaters".

And we read that 3000 people die that day. 

Now…that’s pretty heavy and it troubles a lot of people. What kind of a God does this?And while it offends our modern sensibilities, we have to realize is that according to the terms of the covenant, they all should have died. They all swore a blood oath that they would not worship other gods, and then a little more than a month later that’s exactly what they’re doing.

But only 3,000 die.

Now fast forward to Pentecost. A similar scene plays out with all the parallels we’ve mentioned. But instead of calling out the sin of the people and then having to kill the idolaters as Moses did, Peter preaches the first homily in the history of the Church and the people are “cut to the heart,” says Acts 2:37:

“Brethren, what shall we do? And Peter said to them, “Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. 39 For the promise is to you and to your children and to all that are far off, every one whom the Lord our God calls to him.” 40 And he testified with many other words and exhorted them, saying, “Save yourselves from this crooked generation.” 41 So those who received his word were baptized, and there were added that day about three thousand souls. 42 And they devoted themselves to the apostles’ teaching and fellowship, to the breaking of bread and the prayers (2:37-42).

Now did you notice how many people came into the Church that day? 3,000.

In other words, the 3,000 lost through the broken covenant at the foot of Sinai in the old Israel are restored to the New Israel – the Church - because of the New Covenant of Jesus Christ.

This is the birth of the new people of God.

What was dead has been brought back to life through the power of the Holy Spirit – through the sacraments.

Why through the sacraments? Because Peter tells them what they have to do to be saved-  “Repent and be baptized.” And of course, look at what the people devoted themselves to: the apostles’ teaching and fellowship, to the breaking of bread and the prayers. “Breaking the bread” is early church language for the Eucharist.

They were baptized, celebrated Mass and prayed. The same things we are to do today.

So there you have it. The backstory of Pentecost in the book of Acts is the Old Covenant scene at Sinai way back at the birth of Israel as the people of God. And we are the new people of God. 

The Church is the New Israel, the restored and transformed kingdom of God in the New Covenant of Jesus Christ! Thanks be to God for the Holy Spirit! He brings us life. He manifests God in our presence. He continues the power of the resurrected and ascended Christ in our lives.

He draws us closer to our Lord so that we can fulfill our destiny as children of God. Don’t ever stop asking for the Holy Spirit.

Have a happy, blessed Pentecost!

Matthew

P.S. Pope St. John Paul II said that as the spouse of the Holy Spirit, Our Lady's prayers were key to ushering in Pentecost! Join me in 2026 on a PILGRIMAGE to visit the most well-known Marian shrines in Europe, and connect with Mary like never before! Click here for more information!

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