You were likely taught an incorrect understanding of the Bible.
Bold statement, I know, but I say it because I learned only last night that I was taught an incorrect understanding of the Bible. Or rather, it might be more accurate to say that I had never really learned the Bible properly. In any case, I was missing something, and you very well might be missing something key to understanding the Bible. What was I missing?
I was missing the whole purpose of the Bible! "Christopher, how could you miss the whole purpose of the Bible? Aren't you a missionary, shouldn't you know that already?" Yes and no. I knew that the Bible is God's true words for us and that they are His special revelation, an irreplaceable help for us to know Him and live as we were supposed to. That is all still true. But what I didn't know was that throughout the entire Bible, essentially all of human history, God has been a missionary.
This is most true in the first chapters of Genesis. Let me lay it out: chapters 1 and 2, God creates mankind to live in communion with Him; chapter 3, Adam and Eve fail and fall; chapters 4 and 5, the fallenness is confirmed to pass to children; chapters 6 through 9, God resets the world, keeping only the best family so that all would know Him from then on; chapter 10, the earth is repopulated; in chapter 11, man creates the tower of Babel, a third rebellion, and the fall is confirmed; then, in chapter 12, God chooses Abram and promises to use him and bless him so that He can reach the rest of the world. God is continually trying to bring mankind back to Himself so that He can be in communion with them.
What happens after Abraham? God blesses him and gives the same promise to his son and grandson. They multiply greatly. Joseph saves the world by stewarding Egypt's resources and selling its grain. God delivers them through Moses and they are established in Canaan (to put it shortly). But what is their purpose? God promises through Isaiah that they would be a "light to the nations" (49:6). Israel was to be the "royal priesthood" (Exodus 19:6) which would mediate between God and the gentiles. The Israelites were not just God's chosen people, they were God's chosen servants, priests, and missionaries. They were to be so obviously and abundantly blessed by God that every nation would bow to the God who bestowed such blessings on them. They were blessed only so that others would know God.
Obviously, that didn't work so well. Israel continually failed to do be faithful to Him. So God sent His Son, Jesus Christ to bring the gentiles into the pictures and give them the opportunity to join in God's global mission. He told us specifically to "go and make disciples of all nations" (Matthew 28:19).
So, what does all this mean? That means first that God has been trying to reach everyone on earth since man's creation. But secondly, it means that the Church's purpose, it's very reason for being around, is twofold: be the people who are in relationship with God, and bring more people to be in relationship with God. We are to be in relationship with Him always and to be bringing other people into relationship with Him always. He has desired this since we were made, and He has promised to bring it about in the end. The only variable is how we are going to be a part of that fulfillment.