I think Jeremiah 31:33 gives some insight. (Didn't I already mention that?):
But this is the covenant which I will make with the house of Israel after those days, says the LORD: I will put my law within them, and I will write it upon their hearts; and I will be their God, and they shall be my people. Jeremiah 31:33 RSV
In our daily walk with the Lord, at a time of his choosing, he teaches us his (Devine) Law/Commandments. It takes time, as he wants us to understand the (Devine) Law/Commandments.
Don't you realize that you regularly avoid discriminating between the Law as a set of moral requirements and the Law as a system, or covenant? When you refer to it, via Jer 31, as a "covenant," you are identifying it ambiguously, and not specifying what you mean.
Are you saying the covenant of Mosaic Law is being played out within our heart, or are you saying that God's moral values are being played out in our heart *apart from* the Law of Moses? Explaining this would go a long way towards ending this conversation in a satisfactory way!
For example, someone in the OT era might say that the Law of Moses is being played out in his heart, as he continues to follow all 613 requirements, observing temple, priestly, and sacrificial laws. But Most Christians today would admit that the value of the Law is largely *testimonial,* and not applicable as a covenant any longer. The way it is played out in our heart is through its fulfillment in a *brand new covenant,* the covenant of Christ. Since he fulfilled all 613 requirements of the Law, we simply follow him and thus play out the Law of Moses in terms of its fulfillment in a brand new covenant.
Perhaps you don't have the means or the wish to address this? But failing to answer this leads me to see your statements as inadequate expressions of an important issue here.
Many wish to maintain the value of the Law by reinterpreting the Law of Moses in a NT context, rather than see it as a *completely different covenant,* fulfilling the old one. They reinterpret the Sabbath to be Sunday observance. They reinterpret OT feasts to be a continuation of the observance of those feasts, although recognized as fulfilled in Christ.
There is this insistence on maintaining the *requirement* of the Law along some parallel track of the original Law. Rather than quote me from Jer 31, why don't you explain how you interpret it, unless you simply are unable to do so in the light of my concerns? Perhaps you don't fully understand what my concerns are?
I've heard a lot of Messianic Jews who insist that they should continue to observe Sabbath or Passover, even though they know it was fulfilled in Christ. Some Christians feel they need to observe Sunday as a kind of replacement for Sabbath observance. Is this your idea of having the covenant of Law in your heart?
Or do you see it the way I do, as omitting the entirety of the OT Law in favor of following Christ as the fulfillment of the Law? There is no need for any observance of any religious day at all, nor is there any need to follow a parallel track with the Law in requiring various festivals or food requirements.
The Law is fulfilled in Christ and in his love. His love fulfills all of the moral commands of the Law, minus all of the infrastructure and law having to do with temporary means of atonement.