The New Covenant was an unconditional agreement God made with the nation of Israel. Therefore, the ministry of the Apostles as recorded in the early chapters of Acts was to the nation of Israel. The Jewish Apostles' teaching was based on the prophecies of a restored physical and spiritual Kingdom of God to the nation Israel. After Israel rejected God's offer of the restored Kingdom, Jesus Christ chose Saul of Tarsus to reveal the mystery that the New Covenant would be a blessing to the Gentiles. One last note on external evidences to the reliability of the Bible.
Archaeology is the study of material remains of past human life and activities.
An archaeologist is the person who conducts the research of those material remains. Here's what some of the great archaeologists and students of archaeology had to say about how material remains of past human life and activities affected the Bible. The excessive skepticism of many liberal theologians stems not from a careful evaluation of the available data, but from an enormous predisposition against the supernatural. The evidence is clear. We should obey God's Word and do what He wants us to do.