There is not a single instance in the entire Bible where blood transfusion is mentioned, primarily because this procedure wasn't even in existence until the 1900's. While the Bible was being written, this medical procedure was still a great many centuries away. Since there is nothing about it in the Word of God, isn't it rather difficult to say that blood transfusions are against the Word of God?
In the Old Testament God says not to take in blood, but he was not referring to taking blood transfusions, he was talking about the actual eating or drinking of blood, primarily animal blood. If anyone actually drank the blood from an animal, they would be asking for some very terrible health problems. Also when an animal is butchered, it must be bleed immediately, or the blood born diseases will infect the meat and more than likely make you very sick, maybe even kill you when you do eat the meat. This was especially true back in those days when there was no refrigeration, and they had to rely on methods like using salt.
The many verses in the Old Testament that deal with blood, all revolve around the preparation of meat for eating. Passages like the following are typical of this.
Genesis 9:4 "But you shall not eat flesh with its life, that is, its blood."
However, there is a world of difference between eating or drinking an animal's blood, and having human life saving blood given to a person through a transfusion.
Deuteronomy 12:16 "Only the blood you must not eat. On the earth you should pour it out as water".
It appears that this law is telling us not to ingest or take in "animal blood", when the animal is slaughtered for food.
A good example of this can be found in the first book of Samuel. It tells of the time when the people of Israel went to war and defeated the extremely sinful Philistines. The Jewish warriors had not eaten anything for sometime, so once the battle was over, the army of Israel descended down upon the herds of animals that the Philistines had owned. These warriors were so hungry that they literally ate the meat uncooked. And in eating the raw meat, they also consumed the blood of the animal.
Then it says in 1 Samuel 14:31-33, "Now they had driven back the Philistines that day from Michmash to Aijalon. So the people were very faint. And the people rushed on the spoil, and took sheep, oxen, and calves, and slaughtered them on the ground; and the people ate them with the blood. Then they told Saul, saying, Look, the people are sinning against the Lord by eating with the blood!"
In the New Testament it does talk about abstaining from blood, but again it is referring to ingesting the blood of animals not only slaughtered for food, but also from those animals that were killed and sacrificed to pagan gods. Acts 15:20 "Except that we should write to them and tell them to abstain from eating meat sacrificed to idols, from sexual immorality, and from consuming blood or eating the meat of strangled animals."
Again this is referring to the consuming of dead animal blood.
The above verse is also talking about actually drinking blood and using blood in sacrifices to false gods and idols. Remember that in the Old Testament times, animal sacrifices to God were extremely common. God wanted Israel to sacrifice animals, and part of that sacrifice was the pouring out of the animals blood on the altar and on other sacred areas, and God did not want any part of the animal blood being drunk or being offered up to false gods.
You have to ask yourself would God punish someone who is trying to maintain the life that he has been given, especially since blood transfusions do save lives and they have been perfected enough so that they now are relatively safe? There is nothing in the Bible about transfusions, nor is there anything in the Bible about organ transplants, or the many thousands of other medical procedures that have only recently come into existence. I think God would be very displeased if a person forfeited his life needlessly. Life is very precious to God and I don't think that he would accept the careless throwing away of a life just because some man, through erroneous interpretation, thought it wrong to take blood transfusions.
Also ask yourself, would God punish someone who donates blood with the intention of trying to save another person's life? Trying to save the precious life of another one of God's own children? That's an act that shows great love for your fellow man. I think that God would look very favorably on the person who is trying to save the life of another by giving some of his own blood. And that may also be another reason why God allows the blood in our bodies to be renewed rather quickly.
It is very true that there is still a possibility that a person can acquire Aids from a transfusion. But that isn't God's fault. Man has created the Aids epidemic all by himself, and instead of stoping the evil practices that causes AIDS, he instead greatly increases doing those exact same things that spread the disease. The last thing that sinful man wants to do is stop committing those sins that causes Aids in the first place.
Man has advanced in all areas and blood transfusion is only one of them. God would take a very dim view of someone who could save their life or the life of another, but didn't, all because he was under the mistaken belief that blood transfusions are against the Word of God.