Having performed two marriage ceremonies for the last few weeks, I have given a lot of thought to the whole concept of the “Marriage Covenant”
As well, I am reminded of this concept as articulated by the former chaplain of Duke University, Rev. Will Willimon. I am indebted to his thoughts about “God’s Law” being written on our hearts.
A distinguished Christian ethicist said that "character" is who you are when nobody else is looking. Character is who you are all the way down, deep. Or as the prophet Jeremiah might put it, character is what you have "written on the heart." Jeremiah said that for most of our history with God, we had to have God's way, God's law written on tablets of stone. But there will be a time when God's law will be written on our hearts. Good character is not a matter of accurately reading and obeying a set of rules but rather it is a matter of having something on the heart. Good character is when you are able to sing the song without having to read the notes. You know it "by heart." We say that we acted "out of intuition" or "just from second nature."
What we may mean is that we did them because a new covenant was written on our hearts. God graciously enabled us to do the right thing without having to think about it. Deep within us was a divinely implanted sense of what ought to be done.
Think about this matter of the "new covenant written on the heart" in much the same way that you think about faithfulness in marriage. When you are married, in the "Service of Holy Matrimony," the minister asks that the bride and groom promise to be faithful to one another, "till death us do part." A rule, a law is held up before the bride and groom, a law that they are to obey. They must respond, out loud, before God and witnesses, promising that they will always be faithful to one another in keeping the vows of marriage. Now in the first days of marriage, presumably there are situations when the bride and groom need to be intentional about keeping their promises of fidelity. Maybe they will be faced with some circumstance in which they may have to say to themselves, “I have made a vow to be faithful. I have got to keep my vow no matter what. I made a promise in front of God and everybody. I've got to keep my vow."
But in most marriages, over time, the couple discovers that they are no longer trying to be faithful. They are no longer keeping a promise by thinking hard about being obedient. They simply are faithful. It is as if God has written a covenant upon their hearts. That which previously had to do with their brains they now do with their hearts. They are faithful, "by heart." Well, the promises of marriage, when marriage works its magic, are just like that. We wake up one day and we realize that we are no longer trying to be faithful, or being obedient; we just are faithful. We are keeping the promises of marriage "by heart." The covenant we thought we were obeying has now been graciously written upon our hearts. We don't have to consciously, think about obeying it anymore because it is simply who we are. God has written God's law on our hearts.