Question: "What does the Bible say about eating/drinking blood?"
Answer: In Acts 10, the apostle Peter began to realize just how different this new Christianity was from Judaism. While praying on a rooftop, waiting for lunch, he had a vision. A sheet was lowered from heaven, containing many different types of animals. A voice encouraged him to eat. Peter balked, realizing that some of the animals in the sheet were forbidden under Jewish law. Three times the sheet lowered, and three times Peter refused.
The vision had a dual purpose. The most obvious was that, under the New Covenant, the ceremonial rules about dietary restrictions had been lifted. Christians are to be set apart and recognized by their love (John 13:35), not by their lunches. The second, and deeper, meaning was that Christ’s salvation was open to Gentiles just as it was to Jews. Immediately after the vision, Peter received a visit by messengers from a (Gentile) centurion named Cornelius who was ready to accept Christ.
Carnivorous Christians know and enjoy the message of Peter's vision. But the vision does not directly address the subject of eating blood, unless that’s included in the revocation of kosher law.
The Bible’s first prohibition against consuming blood comes in Genesis 9:2-4, where God tells Noah, "Everything that lives and moves about will be food for you. Just as I gave you the green plants, I now give you everything. But you must not eat meat that has its lifeblood still in it." This prohibition was most likely a ban on eating raw blood (i.e., uncooked meat). For the first time, animals were an allowable food source, and God was making sure that Noah did not eat them raw. A Jewish Targum comments on this verse: "But the flesh which is torn from a living beast at the time that its life is in it, or which is torn from a beast while it is slain, before all its breath is gone out, ye shall not eat."
Later, the prohibition of Genesis 9:4 is iterated in the Law of Moses. Leviticus 17:14 gives the reason behind command: “For the life of every creature is its blood: its blood is its life.”
It’s important to understand that New Testament believers in Christ have freedom from the Law, and we are to “stand firm” in that liberty (Galatians 5:1). We are not under the Law but under grace. “Therefore do not let anyone judge you by what you eat or drink” (Colossians 2:16). So, eating a rare steak, blood sausage, blood pancakes, blood soup, or blood tofu may not be palatable to all Christians, but it is allowable.
There is another passage to consider. In Acts 15, a question arose in the early church concerning what was necessary for salvation. Specifically, did a Gentile need to be circumcised in order to be saved (verse 1)? The issue came up in the church in Syrian Antioch, which had a mixture of Jewish and Gentile converts. To address this important issue, the leaders of the church met in Jerusalem for the very first church council. They concluded that, no, Gentiles did not need to follow Mosaic Law; circumcision is not part of salvation (verse 19). However, in verse 29, the leaders compose a letter with these instructions for the Gentiles in Antioch: “You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality. You will do well to avoid these things.” At this point, we must keep the context foremost in our minds. These four commands from Jerusalem to Antioch all dealt with pagan practices associated with idolatry. Most, if not all, of the Gentile converts in Antioch were saved out of paganism. The church leaders were exhorting the new Gentile believers to make a clean break from their old lifestyles and not offend their Jewish brothers and sisters in the church. The instructions were not intended to guarantee salvation but to promote peace within the early church.
Later, Paul dealt with the same issue. It is perfectly all right to eat meat offered to idols, he says. “Nothing is unclean in itself” (Romans 14:14). But if eating that meat causes a brother in Christ to violate his conscience, Paul “will never eat meat again, so that I will not cause them to fall” (1 Corinthians 8:13). This was the same concern the Jerusalem leaders had in Acts 15: if the Gentile believers ate meat with the blood in it, the Jewish believers might be tempted to violate their conscience and join them in the feast. One’s conscience is a sacred thing, and we dare not act against it (see 1 Corinthians 8:7-12 and Romans 14:5).
In short, ordering your steak rare or well done is a matter of conscience and of taste. What enters the mouth does not make us unclean (see Matthew 15:17-18). Eating black pudding may not appeal to everyone, but it is not a sin. We live under grace. We have liberty in Christ. Others may have different convictions about food and drink, and in that case we voluntarily limit our freedom in order to better serve them and God. “Let us therefore make every effort to do what leads to peace and to mutual edification” (Romans 14:19).