Jesus said that the Kingdom of God is like yeast. As yeast is worked into the dough and changes its structure positively, so the gospel is dispersed into societies and changes them from the inside. To mix the yeast of the gospel into societies, Jesus sent His disciples out to make disciples of all nations: "You shall receive power when the Holy Spirit has come upon you; and you shall be witnesses to Me in Jerusalem, and in all Judea and Samaria, and to the end of the earth" (Acts 1:8).
Jerusalem is pronounced Yerushalaim in Hebrew. In this city Jesus was crucified, raised from the dead, and ascended to heaven, and to this city He will return. In Jerusalem, the Holy Spirit came into the hearts of believers, inspiring them to spread the gospel worldwide. The Acts and letters of the apostles show how the yeast spread throughout the Roman empire in the first century. When the yeast of Yerushalaim has done its work, Christ will return to renew heaven, earth, and Jerusalem.