Fisherman:
Like everything else, medical advice is dependent upon the context in which it is given. An obstetrician and a dermatologist might have two entirely different things in mind when directing a patient to, "abstain from alcohol."
Regardless, blood is not comparable to alcohol inasmuch as it had a purpose in the body long before the fall of man and the need for a Redeemer ever arose.. If you recognize the difference between eating a human kidney for Sunday dinner vs. the transplantation of a human kidney so that it can continue to act as a kidney, (And I assume that you do) then analogies to simple compounds that are broken down and metabolized regardless of the avenue of egress don't really hold up.
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ῥώννυμι is an interesting word that can be translated in many different ways and the JW's, to my knowledge do not assign any theological significance to their rending:
"The comment “Good health to you” was not a promise to the effect, ‘If you abstain from blood or fornication, you will have better health.’ It was simply a closure to the letter, such as, ‘Farewell.’"
(A similar statement appears in the study edition of the RNWT)
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It's easy to say the Mosaic law was abolished, but at the time of the Decree, that idea could have gotten you killed. (We're talking about a conflict that eventually cost both Paul and James their lives.)
Here was the problem and the solution linked together by the Bible writer himself:
“You behold, brother, how many thousands of believers there are among the Jews; and they are all zealous for the Law. But they have heard it rumored about you that you have been teaching all the Jews among the nations an apostasy from Moses, telling them neither to circumcise their children nor to walk in the [solemn] customs....As for the believers from among the nations, we have sent out, rendering our decision that they should keep themselves from what is sacrificed to idols as well as from blood and what is strangled and from fornication.”
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Transfusion can't be argued one way or the other from the Bible, but that doesn't justify sophistry. Cofty's argument is short, simple and should be enough, but if you believe there is either a physical, moral or ontological equivalency at stake here, then it is up to you to demonstrate it and not simply equivocate.