The Lord gave King Solomon all the land between the River Euphrates to the Border of Egypt: Brook of Egypt. He gave King Solomon the land, all the way from the Red Sea to the Sea of the Philistines: The Mediterranean Sea (For references, read here). But Solomon speaks of a son who will surpass his dominion in Psalm 72. This Son will have dominion over the entire earth: “Give the king your justice, O God, and your righteousness to the royal son!… May he have dominion from sea to sea, and from the River to the ends of the earth!”
There is an echo of this promise when Jesus sends out His apostles from Jerusalem: “But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth.”
As the Church we are spreading out into the farthest corners of the earth, into the deepest prisons, into the grittiest industry, and the remotest jungles, as witnesses to the Name of Jesus Christ. The promises are no longer limited to a strip of land called Israel. Rather, the land is the world. The promised land is no longer the Euphrates River to the Brook of Egypt, but the River to the ends of the earth.
In the Old Testament, the command was to drive out the Philistines, to drive out evil by the sword. In the New Testament, the Royal Son whom Solomon speaks of sends out His apostles with a glorious message: repentance and forgiveness of sins. “ and said to them, “Thus it is written, that the Christ should suffer and on the third day rise from the dead,  and that repentance for the forgiveness of sins should be proclaimed in his name to all nations, beginning from Jerusalem.” (Luke 24)
This gospel proclamation is now the sword that goes out into the land: “ In his right hand he held seven stars, from his mouth came a sharp two-edged sword, and his face was like the sun shining in full strength.” (Revelation 1:16) We have no King but Christ, and His kingdom stretches from the River to the end of the earth. We fight for this kingdom primarily by the proclamation of the gospel. This was how the Reformation did so much damage and brought times of rain to a weary 16th century world.