Chickens and Eggs
Here's a question... Which came first Christianity or Judaism?
The Hebrew trace their religion all the way back to Abraham. So on the surface the answer is obvious... But does piety begin with that paterfamilias?
What of Noah? What of Noah's sons? Where they not both pius? If one calls those pius men from Abraham onward Hewbrew... and from Christ on Christian... what does one call those who came before Abraham?
Noah was not circumcised. He didn't avoid certain foods. Nor is there any record of him honoring a particular sabbath or another. He kept no feasts... and yet there can be no doubt that he was a man of God.
Piety existed before the Law given to Moses. It existed in men who were described as such not for keeping any laws, but for their love of the Lord and their treatment of others. Therefore I should say that if one were to describe these men as Christian, in fact if not in name, then one wouldn't be far from the truth.
Christianity is not an Abrahamic Religion. Its far more ancient than that.