Matthew 24:3

In Jesus' response, He concentrates almost entirely on the second question—the signs of His coming and of the end—and the question of when is answered mostly in their aggregate. The closest He comes to answering when appears in verse 14: The end will come when the gospel has been preached in all the world as a witness to all the nations. Only He knows when this goal will be reached.

Richard T. Ritenbaugh
The Four Horsemen (Part One): In the Saddle?

2 Corinthians 5:18-19

Part of the responsibility of the church of God in preaching the gospel around the world is to inform mankind how they can be reconciled to God. In many cases, people do not even know they are separated from God. However, all have been separated from Him, and all need to be reconciled to God through the redemption offered in Christ's payment for sin. To do this, we must also proclaim what sin is, as many are equally ignorant of what constitutes sin. Doing this enables them to judge their need for reconciliation through Jesus Christ.

Preaching the gospel is not just about the Kingdom of God but includes many attendant features that flesh out understanding necessary for establishing communion with God.

John W. Ritenbaugh
The Offerings of Leviticus (Part Six): The Sin Offering