Paul makes it clear that the gospel he preached was specifically how Christ died for our sins, was buried, and rose again the third day. The Lord and his disciples did not preach this prior to the cross. Their message was the good news of the restoration of the kingdom to Israel. It would include a physical deliverance from their enemies so they could serve God without fear.
Luke 1
67 And his father Zacharias was filled with the Holy Ghost, and prophesied, saying,
68 Blessed be the Lord God of Israel; for he hath visited and redeemed his people, (a physical redemption)
69 And hath raised up an horn of salvation for us in the house of his servant David; (a physical salvation)
70 As he spake by the mouth of his holy prophets, which have been since the world began:
71 That we should be saved from our enemies, and from the hand of all that hate us; (Israel)
72 To perform the mercy promised to our fathers, and to remember his holy covenant; (to the nation of Israel)
73 The oath which he sware to our father Abraham,
74 That he would grant unto us, that we being delivered out of the hand of our enemies might serve him without fear,
75 In holiness and righteousness before him, all the days of our life.
Even after the cross, the disciples were looking for the restoration of the kingdom of Israel because that's what they had been preaching.
Acts 1:6 When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?