Jesus says, “I came to bring fire to the earth and how I wish it were already kindled.” (Luke 12:49)
How can we understand this fire?
Read 1 Kings 18:17-40, note especially Elijah’s prayer, the fire is to show the people who God is. Is it Baal? No. The God of Abraham, Isaac and Israel is God. “YHWH is God.” ( vs. 39) The fire is also to show the people, “that thou hast turned their hearts back.” (I Kings 18:37)
Jesus speaks of the fire and “the baptism.” They are the same thing. He is speaking about his cross.
The cross is that which is sent down from heaven so that the people, both Jews and Gentiles may know who is Lord and who has forgiven them, “turned their hearts back.”
The cross is the mercy, the “bowels” of the Lord, that is, as we would put it today, his heart. This is why Jesus is “restrained” (Luke 12:50)
Read Isaiah, the prophet asks, “are thy mercies (or bowels) restrained towards me?”
We learn more about this constraining or restraining of mercies from Joseph. Read Genesis 43:31 and Genesis 45:1
This also shows us why “God waits” to be merciful (Isaiah 30:19) It is not because God is being cruel by delaying. Rather, God is waiting for the right time, restraining his overwhelming love for us. As it says in Romans 5:6 “At the right time Anointed died for the ungodly.”