How will they hear?

Genesis 12:1-3 ESV

Now the Lord said to Abram, “Go from your country and your kindred and your father’s house to the land that I will show you. And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed.”

Romans 10:12-15 ESV

For there is no distinction between Jew and Greek; for the same Lord is Lord of all, bestowing his riches on all who call on him. For “everyone who calls on the name of the Lord will be saved.”  How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent? As it is written, “How beautiful are the feet of those who preach the good news!”

Rev. Dwight Yoo

The story of Joseph reminds readers of the promise that God made to Abraham. The people would be many and would bless the world. Sarah bears a son in her old age. From that lineage, we get Jacob who becomes the father of the tribes of Israel. Under Joseph, Laban and all of Egypt are blessed. Egypt, as a nation, was saved from famine. And at the same time, through the same means, the family of Jacob is saved.
But God's plan is bigger than just saving from famine. From Israel, we get salvation from sin; we get Jesus. He saves people and blesses every tribe and nation. Jesus is the fulfillment of God's promise to bless all the people of the earth. Joseph is only a sign pointing to Jesus. Through faith in Christ, we are heirs to the promise given to Abraham.

Galatians 3:26-29 ESV

for in Christ Jesus you are all sons of God, through faith. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus. And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.

In addition to this inheritance, we are also given a purpose to gather to God and bless the nations. We have a role to play in God's plan. Jesus says:

Matthew 28:19-20 ESV

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.”

Romans 10:10-15 ESV

For with the heart one believes and is justified, and with the mouth one confesses and is saved. For the Scripture says, “Everyone who believes in him will not be put to shame.” For there is no distinction between Jew and Greek; for the same Lord is Lord of all, bestowing his riches on all who call on him. For “everyone who calls on the name of the Lord will be saved.”  How then will they call on him in whom they have not believed? And how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent? As it is written, “How beautiful are the feet of those who preach the good news!”

This is the sole reason why we are not simply whisked away when we've professed faith in Christ. We are all called to play a part in this work. This leaves us with three possibilities. We can be going, we can be sending, or we are being disobedient. God does not give us the option of opting out. We are called to  sacrificially die for salvation of others.

John 12:24 ESV

Truly, truly, I say to you, unless a grain of wheat falls into the earth and dies, it remains alone; but if it dies, it bears much fruit.

God does not bless us for our benefit alone. He blesses us so that we can be a blessing. We are charged to live a life to seek other's needs rather than our ease. God does not give a promise of security on top of a life of ease, but rather He gives a massive promise of security for those in merciful service through suffering. (Piper)