What is the Gospel in the context of the Christian faith?

The Gospel is the foundation of the Christian faith and is detailed in Bible through the account of Jesus Christ's birth, earthly ministry, crucifixion, and resurrection.  The core tenant of the Gospel is the separation of sinful people from a holy God.  This sin required a perfect sacrifice for people to be brought back into relationship with God and entry to heaven.  Jesus lived the perfect life that people could never live on their own, and died as a living sacrifice on our behalf.  Now, whoever places their faith in Jesus as a free gift of grace is brought into right relationship with God and is considered to be saved, or born again.