The gospel message of the Acts of the Apostles is presented through the preaching of Peter and Paul (and the martyr St. Stephen). It’s clear that the message of the apostles is that Christ is risen from the dead. They proclaim resurrection.
The preaching is fairly consistent. Jesus was a good man and a miracle worker. You (or they when addressing a gentile audience) put him to death on a cross. God raised him to new life thereby proclaiming him Lord and Christ. Jesus is the judge of the living and the dead and is able to distribute forgiveness of sins and the gift of the Holy Spirit. The response to this news is to repent and be baptized.
A couple of interesting things to note:
1) The role of the cross in the Acts of the Apostles is not as a payment for sin, but as a wicked thing done to Jesus.
2) The grounds of the forgiveness of sins is the authority that God has given Jesus in the resurrection.
Now, the New Testament has plenty more to say about the cross - and Luke (the writer of the Acts of the Apostles) has plenty to say about it in his gospel. The language of a sacrifice for sins, of redemption, of Christ dying ‘in my place’ are scattered all across the epistles and gospels. Just not in the Acts of the Apostles and these early proclamations of the good news.
What do I take away from this? That the gospel is first the proclamation of who Jesus is. If you want to boil down the news of Christian faith, it is about Jesus, not about me. It’s ‘Jesus is Lord and God raised him from the dead’ and not ‘I can be forgiven and find purpose, hope and meaning in life’.
It might be a subtle distinction, but I think it’s an important one. The story is not mine, it’s about Jesus.
Alleluia, Christ is risen!
The Lord is risen indeed. Alleluia!