I'm quite certain that uncircumcism of heart does not relate to either Jews or Gentiles but to unbelievers. Certain also that Jews and gentiles becoming one is the foundation of Christianity in which case neither is in the position of keeping the law. Contrary to what some are espousing.
Maybe it would help to lay out the missing pieces we each are using but haven't said, so that they won't be guessed at wrongly (which is only natural to do).
Using my own paraphrasing (which will always be less perfect than scripture, inevitably) --
Here's what I understand, and where I'm at --
1. We are only saved if we believe in Christ as the Son of God, risen, our redeemer, that we rely on for our salvation.
2. Because we truly believe in Him, we are changed, and become better than we were, over time.
3. We continue to be changed, over time, by our faith, and the power of communion.
4. We continue to be changed, over time, by our faith and by
listening to His words, such as His commandments, like "love one another", and by the parables also, such as the parable of the unforgiving debtor, which teaches us to totally forgive even in our heart. Because we truly listen, then we begin to do as He said (if we truly listened). Sometimes this is harder to do.
5. We are still in the condition of having real freedom to choose and act.
6. So we will sometimes fall into temptations, like social pressure to exclude someone, for instance, as Peter did towards the uncircumcised gentile converts, for instance, until later Peter changed, and reversed himself, and clearly said that physical circumcision is not necessary. So we can not only stumble in clear sins, but also in excluding brothers and sisters for mere judging their actions too finely (not about flagrant sinning, but about mere disagreements on subtle points).
7. Because we can stumble and fall under temptations, our Lord gave us a way to pray for aid. This is of extreme value, because it's possible to stray far from Him if we do not have divine aid to deliver us from evil. He gave us the prayer in Matthew 6 because we actually do need it (instead of not really needing it). Failing to move out of a sin is possible even for a believer because it's possible to ignore our conscience.
8. Because it's possible to ignore our conscience, it's possible to even eventually fail in our faith itself even -- as He told us in Matthew 7:24-27.
9. To avoid this collapse, we must actually do just as He said in Matthew 7:24-27.
10. Because of this, faith without works will indeed lead to death. Because at times we have real choices, we actually need to know what to do, because sometimes we can't manage to listen to the quieter voice inside, due to external noise.
11. As He told us in John chapter 15, we can only do true, real fruit only by remaining in Him, that is dwelling in His Words, that is his actual words He said to us, hearing them, listening to them, taking them into our hearts. There isn't any substitute I know of to replace this essential listening and hearing --
"My sheep listen to my voice; I know them, and they follow me."
12. The listening/hearing isn't automatic, but we must actually look to Him by bringing our minds back to Him, an action on our part. We must listen to Him as an action on our part. He saves us, and this happens
if we follow Him. Sometimes this is harder to do due to temptations, such as a temptation to strike at someone in some way, or be greedy, etc.
13. Because we do stumble at times, we must confess in our hearts to our Father, and turn from our sins. When we confess this way, we are forgiven
and restored. As it were, we are turning from that path of that sin, and back onto His way, the "narrow road", and with aid from above.
14. Of great aid to us are Christ's emphatic and sharp warnings and commands, such as --
"Forgive, and you will be forgiven."
"The measure you use will be measured to you."
And the very sharp warnings and commands in Matthew 25:31-46 for instance, which help us understand that these are not optional extras, not extra treasure in heaven, but essential and fundamental requirements. (if you are the one nearby to the person in need, and they are not already being taken care of, then it's for you to act)
I'm sure I didn't word this perfectly (scripture is better), and likely left out even something I indeed believe and do, but I think these are many of the key things as best I know them so far.