I don't think you can say that heart circumcision has "replaced"physical circumcision because (1) heart circumcision was also a part of the Old Covenant Torah, and (2) you can't replace something inner with something outer. YYou can say that the inner remains or continues but you can't say it replaces it.

The New Covenant is about total immersion in Messiah, the Old was about cutting off the old nature, which was actually impossible under the Old Covenant which only foreshadowed what was to come in Messiah. Physical circumcision was the visible, outer covenant before witnesses of an 8 year-old (or older if a convert) that involved shedding of our blood. Yah'shua has fulfilled that by being our blood shedding and the means to remove the carnal nature through crucifixion. The shedding of blood is no longer required. What is now required? Total immersion in Messiah so that we are fully IN Him. Baptism is a covenant sign for New Covenant believers do indicate many things but including a witness that Yah'shua is out cutting-off of sin. So I think the comparison of physical circumcision with water baptism is valid. (I do not think it was an Old Covenant mikveh though it paralleled it).

I can´t see any direct references in the New Testament about baptism as a parallel with the circumcision, but we can read about the baptism as a a parallel to the event when the Israelites went through the Red Sea. I use the heart as more as an metaphorical picture as the prophet Ezekiel did, not as an appropriate theological view of circumcision and the meaning of it. What I mean is that the it´s important to have a circumcised heart when you obey the commandments, otherwise You will be as the unsaved Jews or the old Israelites how sometimes obeyed in their own strength.You say that heart circumcision was also a part of the Old Covenant Torah. Yes, but they failed because of their hearts condition was never changed. I heard from the the reformed church I´v visit that they used the circumcision as an argument for baptismal of infants. I have some problem to understand why You can´t say that You replace some inner with some outer. For me it´s more what You are focusing on, not replacing the spiritual meaning of it. of course it´s till there. I believe we do many things that are replacing the old covenants applications, for example the offering systems. Isn´t valid to say that praying has replaced for example the sacrifice of peace-offering?

I certainly understand where you're coming from and I most definitely agree about the importance of right focus. Whether one ordinance had "replaced" another one or not is probably just academic anyway - the important thing is that Scripture says physical circumcision is of no religious value any longer under the New Covenant, that heart-circumcision is the "main thing", and that baptism by full immersion is the outward sign of rebirth and covenental entry into the new Covenant and Messianic Community.

Interesting that the Reformed Church use physical circumcision of babies as a justification for infant baptism. If that were so, then their use of sprinkling instead of immersion could only be justified on the basis that you might risk drowning a baby if you immerse it, thereby indirectly accusing the Creator of 'forcing' man to modify a heaven-given ordinance so as not to accidentally kill infants.