Here's a key excerpt from the article:
Keller answered this year's question for the Christian Vision Project, "Is our gospel too small?" (The article is not yet available online.) In so doing he took a stab at defining the gospel. "Through the person and work of Jesus Christ, God fully accomplishes salvation for us, rescuing us from the judgment for sin into fellowship with him, and then restores the creation in which we can enjoy our new life together with him forever."Your salvation is bigger than just your conversion or justification, and it's bigger than just something that happens to you in isolation from others.
Is God's plan to renew creation part of the gospel message? If so, is it the center of the gospel or a peripheral component of the Good News? Again, how you answer these questions affects how you will live, and how you will expect fellow church members to act.
"When the third, 'eschatological' element is left out, Christians get the impression that nothing much about this world matters," Keller wrote. "Theoretically, grasping the full outline should make Christians interested in both evangelistic conversions as well as service to our neighbor and working for peace and justice in the world."