2:1 And when the day of Pentecost was fully come, they were all with one accord in one place.
Those listed in Acts 1:13-14 were of one accord and were assembled together in Jerusalem.
2:5 And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven.
The Jews and proselytes in the city investigated what was going on.
2:8 And how hear we every man in our own tongue, wherein we were born?
The apostles, filled with the Holy Ghost, began to speak in tongues.
2:11 Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.
Speaking in tongues, as can clearly be seen above in verses 8 and 11, involves the ability given the apostles to speak and be heard in a specific language, not of their own. It was a sign given them to substantiate their ministry.
Peter, standing with the eleven, spoke.
2:16 But this is that which was spoken by the prophet Joel;
Pentecost and the filling of the Holy Host was prophesied by Joel. This was a fulfillment of prophecy in Joel 2.
2:22 Ye men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles and wonders and signs, which God did by him in the midst of you, as ye yourselves also know:
2:23 Him, being delivered by the determinate counsel and foreknowledge of God, ye have taken, and by wicked hands have crucified and slain:
2:24 Whom God hath raised up, having loosed the pains of death: because it was not possible that he should be holden of it.
In the above verses it should be noted that Peter was not addressing the newly formed church, the Body of Christ, but rather, Israel only. Peter preached Jesus as Christ and his resurrection. The resurrection of Jesus Christ would establish the future promise of His Kingdom on earth. This promised Kingdom would put him on the throne of David; enable Israel to reign and rule with him over the nations; and be a light of salvation to the Gentiles, thru the indwelling of the Holy Spirit.
2:36 Therefore let all the house of Israel know assuredly, that God hath made the same Jesus, whom ye have crucified, both Lord and Christ.
2:37 Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?
Peter, in the above verses, states that Jesus is both Lord and Christ. Jesus rose from the dead, showing his diety, that he is the Son of God.
In verse 38 below, Peter shows that Jesus is the Christ, the Messiah, the Saviour of Israel, who alone can forgive the sins of the nation of Israel.
2:38 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.
2:39 For the promise is unto you, and to your children, and to all that are afar off, even as many as the LORD our God shall call.
Peter is only offering the above promises of remission of sins and the gift of the Holy Ghost to Israel and those Gentiles who would come to God thru Israel.
2:41 Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.
The believers were baptized according to the Israel program of recognition of the name; the authority; and the idenity of Jesus. They were added to them, the church of the Kingdom to come, not the Body of Christ.
2:42 And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers.
2:43 And fear came upon every soul: and many wonders and signs were done by the apostles.
2:44 And all that believed were together, and had all things common;
2:45 And sold their possessions and goods, and parted them to all men, as every man had need.
They sold all they had and provided to all according to the commandment to Israel by Jesus in Matthew 13:46 and 19:21.
2:46 And they, continuing daily with one accord in the temple, and breaking bread from house to house, did eat their meat with gladness and singleness of heart,
2:47 Praising God, and having favour with all the people. And the Lord added to the church daily such as should be saved.
They were in one accord as well. The church here is not the Body of Christ. The church here are the believers in Christ who were promised entrance into the Kingdom on earth. The kingdom which is postponed and interrupted by our Dispensation of Grace.