The message of the early church was the resurrection of Jesus from the dead.

But God hath raised Him up, having loosed the pains of death, because it was not possible that He should be held by it.  (Acts 2:24)

The apostles recognized the power of His resurrection. The early preachers of the gospel gave great prominence to the resurrection of Jesus Christ. The Apostle Paul declared that he sought to "know him and the power of his resurrection.” (Philippians 3:10)

They recognized the power of his resurrection. In Romans 1:4, Paul said that Christ was "declared to be the Son of God with power..... by the resurrection from the dead.”  The resurrection from the dead was a conclusive demonstration that Jesus Christ was the Son of the living God.

Paul makes it clear in 1 Corinthians 15 that there is no remission of sin without the resurrection. If Jesus has been raised, then we too have hope for a future resurrection. If Jesus has not been raised, then there is no hope. We are still in our sins. Jesus is just a false messiah. Jesus’ disciples are false witnesses. Our salvation was not provided only by Jesus’ cross.  Jesus’ resurrection was absolutely necessary. It wasn’t enough for Jesus to die. He had to defeat the final enemy, death itself.

And killed the Prince of life, whom God hath raised from the dead; whereof we are witnesses. (Acts 3:14-15)   
Unto you first God, having raised up his Son Jesus, sent him to bless you, in turning away every one of you from his iniquities. (Acts 3:25-26)   

In our day the thought of life after death has been diluted.  Hollywood has given us zombies, the living dead, vampires, reincarnation, ghost whisperers, mediums who speak with the dead, etc. 

The impact has been lost on our generation.  Nevertheless, the resurrection of Jesus from the dead is unique in history and has never been claimed by the followers of another religion or religious figure.  It is the central message of the church.