Throughout my years in ministry, I worked with many men and women who had chosen to become Christians. I watched their faces shining with joy as they came up out of the pool. I saw their fervor as they became active in the church community, and brought their children to classes.
Some of these men and women remain active in the church community and have the same or greater love of Jesus as they had in the first flush of their joy in becoming a Christian. Others either found it too difficult to maintain the lifestyle changes Christianity calls for, or lost their fervor and became "sometime" followers of Christ.
As I read this passage about Israel, I remembered these people. God is reminding them of the fidelity and love they once felt for the God who brought them out of Egypt and who saved them over and over again form those who would destroy them.
Now, they had lost their fervor for doing the will of God. They had turned to a life that was less demanding, becoming more selfish and less just. They took for granted that God was there – if they thought about God at all!
Jeremiah is reminding them of their former kindness toward one another and their hearts that were turned to him and not to idols.
For those whom I worked with who decided to become Christians, there will not be any invasion that will take away everything they have, and I am sure that the Lord will rekindle in them the love they once had like the marriage that cools after the honeymoon, but blossoms again as time goes by.
For the Israelites, not listening and turning back to God will have much graver consequences.
The message for us is also clear: if we have lost the fervor of our first coming to Christ, we need to do something about it.

