John 15:27 "And you also will bear witness, because you have been with Me from the beginning."
The disciples are to bear witness of our Lord as the Messiah, and also His divinity, powers, love, sufferings, death and resurrection.
Peter preaching to the Jews
Act 2:22-24 "Men of Israel, hear these words: Jesus of Nazareth, a Man attested by God to you by miracles, wonders, and signs which God did through Him in your midst, as you yourselves also know - Him, being delivered by the determined purpose and foreknowledge of God, you have taken by lawless hands, have crucified, and put to death; whom God raised up, having loosed the pains of death, because it was not possible that He should be held by it."
Peter preached Jesus Christ, the Son of God sent by God to redeem all mankind from sin and from Hades. It is strange that Peter being a fisherman and considered as unlearned should be sent by the Lord to preach to the learned Jews. Since the Jews are knowledgeable in the OT, he used the OT to prove that the Messiah, from the seed of David, must first suffer and then crucified but Death could not hold Him for God would resurrect Him.
Act 2:29-32 "Men and brethren, let me speak freely to you of the patriarch David, that he is both dead and buried, and his tomb is with us to this day. Therefore, being a prophet, and knowing that God had sworn with an oath to him that of the fruit of his body, according to the flesh, He would raise up the Christ to sit on his throne, he, foreseeing this, spoke concerning the resurrection of the Christ, that His soul was not left in Hades, nor did His flesh see corruption. This Jesus God has raised up, of which we are all witnesses."
Paul preaching to Gentiles
Act 17:22-24 Then Paul stood in the midst of the Areopagus and said, "Men of Athens, I perceive that in all things you are very religious; for as I was passing through and considering the objects of your worship, I even found an altar with this inscription: TO THE UNKNOWN GOD. Therefore, the One whom you worship without knowing, Him I proclaim to you: "God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands."
Paul, a Pharisee, knowledgeable of the OT but rejected by the Jews, was sent to the Gentiles. He showed that the God in heaven, whom they worshipped and without any name is the Creator of heaven and earth. He is not an idol but the Almighty God. God wants everyone to repent of their sins for He will come to judge with righteousness through His Son Jesus Christ raised from the death.
Act 17:28-32 "for in Him we live and move and have our being, as also some of your own poets have said, 'For we are also His offspring.' Therefore, since we are the offspring of God, we ought not to think that the Divine Nature is like gold or silver or stone, something shaped by art and man's devising. Truly, these times of ignorance God overlooked, but now commands all men everywhere to repent, because He has appointed a day on which He will judge the world in righteousness by the Man whom He has ordained. He has given assurance of this to all by raising Him from the dead."
Brethren, we too must preach the full gospel of the message of the cross, where we have to walk out our faith to be like Him and be with Him.
1. Redemption by faith,
2. Crucify our flesh
3 Abide in Jesus
4. Keep His words, commands, etc.
5. Baptized in the Holy Spirit
6. Love the Lord
7. Love one another.