Mat 15:24 I am not sent but unto the lost sheep of the house of Israel.
This is an interesting statement given the fact that Christ has changed the other nations of the world more than any other single person. The context is that he says this in response to a Canaanite woman asking him to help her daughter. When you example the Greek, a bigger surprise await you. The phrase isn't "the lost sheep of the house of Israel." It is "the destroyed sheep of the house of Israel" or "destroying the sheep of the house of Israel. In Greek: apollumi (destroyed, destroying) probaton (sheep) oikos (house) Israel.
"Lost" if from apollumi, which means "to destroy utterly," "to kill," and "to lay waste." It is a verb form, specifically, a participle ("destroyed" or "destroying") not an adjective. It can mean "lost," but in the sense of "to lose one's life" and "to lose one's spirit." In English, the past participle (destroyed) is used as an adjective, but in Greek it is either as a verb or a noun (destroying) and is called a "verbal noun." But here, the past adjective form (destroyed) makes more sense, but I like to think that Christ offers both meanings. Christ was sent both to scatter the house of Israel to all parts of the earth and to save those of the house of Israel who had been destroyed by following the smallest rules instead of the larger truth.
This transformation of the house of Israel was what was and is destined to change the world.
Looking at the specific situations, that is, the request for a miracle driving out devils, Christ is also saying that his mission is to drive the devils out of the house of Israel first. However, he doesn't say this in a hostile way. He never uses the term "sheep" (probaton) is a critical way, condemning people for being followers. He always uses it in the positive sense of a group of those for who he is personally responsible.
This is an interesting view of his narrow mission in history. He recognized that within the span of his life, even given his divine powers of healing, he would not change the world directly. His mission was limited. His compassion and powers were focused on his mission. Though it seems cruel, Christ is telling us that suffering will persist because God's plan for the world requires a certain way of unfolding.