What did Les say is the whole fruition of the Gospel?
The whole fruition of the Gospel is the resurrection of Christ: He was raised from the dead, victorious over sin, over hell, over death, and over everything. It is not enough to believe Jesus was a good man or that He died by crucifixion; the resurrection is the bedrock.
Les explains that after the resurrection Peter was no longer afraid of Rome, the Jews, or anyone, because he had witnessed the power of resurrection. Les says this resurrection power has to be the bedrock of our Gospel. It is not enough to believe Jesus was a good man, nor enough to believe He died a crucifixion. The whole fruition of the Gospel is that He was raised from the dead, victorious over sin, over hell, over death, over everything. Paul later trumpets this to the world: we are what we are because Christ not only died but rose victorious over our archenemy, breaking the bonds and shackles of sin.