Acts 2 -  The day of Pentecost arrives.  Jerusalem was again full of people there to celebrate the barley harvest, one of the significant festivals designated by the Law.  The group of Christ followers were in the upper room.  The sudden sound of a violent wind swept right into the room.  Tongues of fire appeared on every one of them.  The Holy Spirit filled them "and they began to speak with other tongues, as the Spirit was giving them utterance." 

What happened in the upper room did not stay there... for the whole city heard the noise and came to find out what was happening.  What they heard simply blew their minds!  No matter what language they spoke.. they heard.. in their own language the "mighty deeds of God".

Peter and the apostles stand up and he begins to speak.  His message is clear:

What is happening was foretold in the book of Joel.
The Spirit has come so that ".. everyone who calls on the name of the Lord shall be saved."
To do that they needed to believe that:
Jesus, performed miracles and signs attesting to Who He was.
He was delivered up, nailed to a cross, and put to death.. by his own people.
God raised Him from the dead, " putting an end to the agony of death, since it was impossible for Him to be held in its power." 
He fulfilled the Lord's promise to David.. an heir to the throne.
His resurrection was witnessed by those now in their presence.
The sending of the Holy Spirit was promised and now fulfilled.

"Therefore let all the house of Israel know for certain that God has made Him both Lord and Christ - this Jesus whom you crucified." ( v36)

These words cut to the heart of those willing to receive it.  3000 came into the fellowship of believers and were baptized. The first true church of Jesus Christ was born.

Father in heaven, You are holy and infinite.  You keep Your promises and fulfill Your Word.  You have given us Your Holy Spirit to bring us to the knowledge of Jesus who is Lord and Christ.
We receive and believe the Truth of Your Word and call upon the Name of the Lord, Jesus Christ to be saved and to live with You eternally.  May we, Your people, from every tongue and tribe and nation walk with You,  be united in You, and be  filled by Your Spirit. May we bear fruit in every good work.
Thank You for saving us and making us Your own.  Holy Spirit give us words to speak so that we might tell others of the good news, that salvation has come through Jesus Christ who loves us and who delivered Himself up for us.  Praise to the Father and to the Son and to the Holy Spirit. Amen.