In Luke 12, Jesus said to his disciples, "I have come to set the earth on fire, and how I wish it were already blazing! Do you think that I have come to establish peace on the earth? No, I tell you, but rather division." The fire he has come to set is the Holy Spirit who has united all those who believe in him into one Body in one Spirit. He has also come to cause division, for he foreknew that there would be many who would not believe in him. It's all part of the spiritual battle to this day.