How big is the gospel? Recently, more emphasis has been placed on the cosmic and corporate natures of the gospel. God is saving or redeeming all things in Christ. God has a cosmic plan to undo all the damning effects of sin. The good news spreads grace 'as far as the curse is found'. Yes, yes and Amen. In my upbringing, this great truth wasn't emphasized much, and I really appreciate the bigness of it.
But... Does the gospel have anything to say about how I, as a wretched sinner, will find a place in God's new world? With the emphasis on the bigness and cosmic nature of redemption, I feel we can go too far in that direction and end up overlooking and undervaluing the individual nature of gospel salvation.
The beauty of the new heavens and new earth is that sin and evil are obliterated, all of God's enemies are destroyed, nothing impure or unholy is permitted entrance. Wonderful. Oh, but wait, we're all sinners (Rom. 3:23), we're by nature God's enemies (Rom. 5:10; Eph. 2:3), and unholy (Rom. 3:10; Rom. 5:6).
A gospel that doesn't address the question of how an individual sinner is reconciled to a holy God is not gospel at all. The full gospel includes the good news that God is redeeming all things, undoing the effects of the curse, and has by grace through faith in Christ reckoned sinners to be saints and included them in his redemptive purposes.
For a great discussion of this, see DA Carson's article 'What is the Gospel? - Revisited' (especially the subheading 'The Gospel in Its Wide and Narrow Senses' starting on pg. 159). This essay appears in the book For the Fame of God's Name: Essays in Honor of John Piper.