reply to post by Mynaeris
No 11 answers your question WHY, it was a sign of the covenant between God and His people.
The "8 days old" part is AMAZING (scientifically speaking),
See quote below from article called
Biblical Accuracy and Circumcision on the 8th Day
by Bert Thompson, Ph.D. at link:
"In Genesis 17:12, God specifically directed Abraham to circumcise newborn males on the eighth day. Why the eighth day? In 1935, professor H. Dam
proposed the name “vitamin K” for the factor in foods that helped prevent hemorrhaging in baby chicks. We now know vitamin K is responsible for
the production (by the liver) of the element known as prothrombin. If vitamin K is deficient, there will be a prothrombin deficiency and hemorrhaging
may occur. Oddly, it is only on the fifth through the seventh days of the newborn male’s life that vitamin K (produced by bacteria in the intestinal
tract) is present in adequate quantities. Vitamin K, coupled with prothrombin, causes blood coagulation, which is important in any surgical procedure.
Holt and McIntosh, in their classic work, Holt Pediatrics, observed that a newborn infant has “peculiar susceptibility to bleeding between the
second and fifth days of life.... Hemorrhages at this time, though often inconsequential, are sometimes extensive; they may produce serious damage to
internal organs, especially to the brain, and cause death from shock and exsanguination” (1953, pp. 125-126). Obviously, then, if vitamin K is not
produced in sufficient quantities until days five through seven, it would be wise to postpone any surgery until some time after that. But why did God
specify day eight?
On the eighth day, the amount of prothrombin present actually is elevated above one-hundred percent of normal—and is the only day in the male’s
life in which this will be the case under normal conditions. If surgery is to be performed, day eight is the perfect day to do it. Vitamin K and
prothrombin levels are at their peak. The chart below, patterned after one published by S.I. McMillen, M.D., in his book, None of These Diseases,
portrays this in graphic form."
"Dr. McMillen observed:
We should commend the many hundreds of workers who labored at great expense over a number of years to discover that the safest day to perform
circumcision is the eighth. Yet, as we congratulate medical science for this recent finding, we can almost hear the leaves of the Bible rustling. They
would like to remind us that four thousand years ago, when God initiated circumcision with Abraham....
Abraham did not pick the eighth day after many centuries of trial-and-error experiments. Neither he nor any of his company from the ancient city
of Ur in the Chaldees ever had been circumcised. It was a day picked by the Creator of vitamin K (1984, p. 93).
Moses’ information, as recorded in Genesis 17:12, not only was scientifically accurate, but was years ahead of its time. How did Moses have access
to such information? The answer, of course, is provided by the apostle Paul in 2 Timothy 3:16—“Every scripture is inspired of God.” "