In the OT the penalty for people who did not observe circumcision was spiritual exclusion from the people. 

Exodus 12:48 tells us  

If a stranger shall sojourn with you and would keep the Passover to the Lord, let all his males be circumcised. Then he may come near and keep it; he shall be as a native of the land. But no uncircumcised person shall eat of it. 

But what about circumcision of heart? First of all the heart as far as we have come into the 21st century, cannot be circumcised, so therefore this verse cannot be referring to something understood by the natural world, the circumcision of the heart must be a supernatural procedure and if we believe God was the one who inspired Moses to record such an incredulous statement, then only God himself is capable to carry out this procedure. This can only be a spiritual procedure. A physical circumcision gives you inclusion to a feast or a heritage, this circumcision of the heart gives you the most privileged inclusion has ever been intended for all of us, and that is to see the heart of God, to feel what He feels, to love what He loves and to hate what He hates. So then we not only obliged to do justice, we are incLed to respond to in-justice, we not only love kindness, we cringe when kindness is not evident, we not only walk humbly not based on our merits, but because we have sinned and fallen short from the glor
y of God, and surely this supernatural procedure must be the prerequisite for anybody to conform into the image of Christ Himself.

We go to doctors, specialists and surgeons and rely on their tests to give us the condition of our physical hearts.

The only ones who know the condition of our spiritual heart is us and our Maker.

Today, can you honestly say that you have the kind of heart that God requires?