It’s necessary for heaven to receive [Jesus] until times of restoration for all the things God spoke about through the mouth of his holy prophets of long ago. - Acts 3 & 4

This part of Acts seems to move energetically and purposely through what transpired in Jerusalem before corruption from within and persecution from without forced many Christians out and thus ignited the explosion of Christian missionary work and the spread of the apostle's message. I get pumped just reading through it.

When you look at Peter’s words to the people and the temple authorities, you don’t see dry speeches. He doesn’t give doctrinal dissertations, though teachings are certainly contained in them. And he doesn’t give motivational speeches intended to encourage people to just be more socially active and live moral lives while quoting “Old Testament examples” here and there, though living a holy life is part of it. In Peter’s words you see him telling the climactic event of the grand epic that Moses and the Prophets were all leading up to, Jesus’ resurrection from the dead! Peter heals this man born crippled so that he can focus (the healing is called a sign) on telling the people and the temple authorities about what Jesus has done to restore all things (as he did this born crippled) and bring about promised the time of restoration.

God made him both Lord and Messiah, this Jesus whom you all crucified! - Acts 2

Here it is, the biblical Pentecost. Now, this shouldn’t go without saying. Pentecost comes from the Greek word for 50, and is another one of the names for the “Feast of Weeks” (Exodus 34:22, Deuteronomy 16:10), or Feast of Ingathering/Harvest/Reaping. This harvest was celebrated 49 days (7 weeks) after Passover (Easter), hence the 50. It celebrated the spring harvest as God’s people thanked him for his goodness for giving them the land as their inheritance, and as they didn't abuse what they had, but instead gave their first-fruits to the Lord in Jerusalem. The whole intricate system of Mosaic sacrifices is something I want to know more about. I agree with the venerable N.T. Wright (http://www.altervideomagazine.com/2011/06/08/old-testament-sacrifices/) that they were about more than just “penal substitutionary atonement,” though that's certainly a key element in at least some of them 

It just blows my mind sometimes when I consider how God worked out all the regulations and festivals in the Torah (Genesis-Deuteronomy) to prepare his people for Jesus the Messiah and illustrate beautifully what Jesus came to accomplish. The Pentecost festival itself was a “party-time” where people feasted and celebrated. How fitting is it that God chose in his plan and foreknowledge (2:23) to institute this festival and use it to harvest souls and start this multi-national (the list of nationalities shows there were people from all over that known world) explosion of getting the good news out about Jesus’ resurrection! And like I wrote on Sunday, Pentecost means Jesus rules, and he’s calling the world to acknowledge it and act accordingly by changing their ways (repenting) and being baptized for the forgiveness of sins so they can, too, become part of the people of God.