The death and ressurection of our Lord, Jesus Christ, was a major turning point in the affairs of mankind. From that point onwards it would no longer be business as usual in the way God and man relate.
The Cross and the Finished Work discusses the overall significance of Christ's mission on earth. When all is said and done, we realise from the word of God that Jesus Christ is the only message of the Scriptures. More than that, we realise that Jesus Christ is all that we will ever need, in this life and in the one to come.
A highly recommended reading.