The whole of Scripture points to people from all over the world coming to a saving knowledge of God through Jesus Christ. Missions is not a modern phenomenon, nor did missions merely begin at the advent of the New Testament. Missions began in the very beginning, in the Old Testament.
There is one world, and everything in it is a creation of God. "The earth is the Lord's and the fullness thereof, the world and those who dwell therein" (Psalm 24:1). This means that everyone is subject to God - no matter who one is, where one is from, or what one believes.
Even Israel in the OT stood as a witness before the rest of the world in order to point to the glory of God. The Psalms routinely call upon all of the nations to worship the one, true God. "Clap your hands, all peoples! Shout to God with loud songs of joy!" (Psalm 47:1).
The Prophets also promised salvation for the world. "It shall come to pass in the latter days that the mountain of the house of the Lord shall be established as the highest of the mountains, and shall be lifted up above the hills: and all the nations shall flow to it, and many peoples shall come, and say: 'Come, let us go up to the mountain of the Lord, to the house of the God of Jacob'" (Isaiah 2:2-3).
Of course, this salvation for the nations comes through the Messiah, Jesus Christ. "Behold, the virgin shall conceive and bear a son, and they shall call his name Immanuel" (Matthew 1:23). And, as Simeon knew, this Messiah was for the nations: "my eyes have seen your salvation that you have prepared in the presence of all peoples, a light for revelation to the Gentiles, and for glory to your people Israel" (Luke 2:30-32).
The NT reveals that God's plan of redemption for the world is through His Church. "You yourselves like living stones are being built up as a spiritual house, to be a holy priesthood, to offer spiritual sacrifices acceptable to God through Jesus Christ... you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into His marvelous light. Once you were not a people, but now you are God's people; once you had not received mercy, but now you have received mercy" (1 Peter 2:5, 9-10).
As one missionary told me, "The world exists because the Church exists." God, who created heaven and earth, can be known. God, who loves His creation, loves the world through the Church. And as Jesus, who has all authority in heaven and on earth, instructed the disciples: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age" (Matthew 28:19-20).
So, we enter the mission field seeking to plant churches so that the world may know and love the God who created heaven and earth.