LEAVEN LESSON TO EXPLAIN THE UNREACHED
Jesus said: The kingdom of God is like yeast, which spreads throughout the whole lump of dough. That could be analogous to the Gospel, spreading *throughout* a given people group, once it's introduced. The Gospel is powerful, like yeast, in comparison to its size--a small amount can permeate and influence the WHOLE lump of dough.
But our message is, "What about those societies/people groups where the yeast of the Gospel has not yet even been introduced!?" Those are the unreached peoples, where the Gospel has not yet been presented! In reached societies, the yeast can and will continue to spread and influence. But we are asking God to raise up prayers and pioneers to take the Yeast of the Gospel and introduce it to people groups that don't have it yet.
May God guide us as we seek to be His ambassadors to the church!