TL;DR: Appearance of evil: Drinking blood was an element of Pagan sacrifice
Are we under obligation to avoid any or all of those 4 things [meats offered to idols, and from blood, and from things strangled, and from fornication] today?
Original context: Pagan sacrifices
These four items appear to be linked together because all of them were elements of pagan sacrifices. According to this essay,
Often, pagan worship included the sacrificing and eating of animals, sometimes with the drained blood being offered as a “course” in the meal. These festivities also generally included sexual participation by the guest in any number of immoral ways. Coffman* noted: “Idol feasts were shameful debaucheries, marked by the most vulgar and immoral behavior.... In fact, it is possible that all four of these restrictions relate to idol worship” (1977, p. 299)
*Coffman, James Burton (1977), Commentary on Acts (Abilene, TX: ACU Press)
Other discussions in the epistles of Paul
The apostle Paul made it abundantly clear that sexual immorality was unacceptable in the church.
1Cor 6:18 Flee sexual immorality! “Every sin that a man does is outside the body,” but he who commits sexual immorality sins against his own body. WEB
Gal 5:19 Now the works of the flesh are obvious, which are: adultery, sexual immorality, uncleanness, lustfulness, WEB
- Eph 5:3 But sexual immorality, and all uncleanness, or covetousness, let it not even be mentioned among you, as becomes saints; WEB
Paul also specifically allows eating of meat which has been sacrificed, as long as it did not produce a bad witness. If a brother or sister in the Lord would be offended, or if someone specifically pointed out that "this meat was sacrificed" -- presumably to test what the believer would do -- then the meat offered should be avoided. It appears that eating the meat was not in conflict with the requirements of the Jerusalem conference if there was no offense. It is not clearly stated in scripture whether eating strangled animals or drinking blood was also ok if it gave no offense, but these seem to be closely related and are not otherwise forbidden to Christians.
Later church practice
Almost all Christian groups today reject sexual immorality as sinful, though there is some variation in what constitutes immorality (some groups even finding premarital relations to be acceptable). Pagan sacrifices seem to be rare enough in Europe and the Americas that little is written about it in most denominations. In practice, most Christians would avoid being seen as an active participant in any sacrifice they consider inappropriate. While most groups say nothing about blood or strangled animals, the Witnesses of Jehovah and the Eastern Orthodox churches do forbid them. Some Pentacostal groups interpret the conference requirements as commands still in effect, but spiritualize them, for example "strangled meat" is careless doctrinal statements.
A Catholic viewpoint:
Notice, neither the letter nor the restrictions were meant for the Church as a whole, but only to the Gentile converts in a certain section of the world. Nor was it making any "dogmatic" statement, but only a practical one. Thus most do not interpret this passage as being meant for all generations of Christians. It was meant to keep peace between the Jewish and Gentile converts in a specific community at a specific time. In addition, it, like the rest of scripture, was prohibiting the consumption of blood 1, not its use in medical operations 3
The Orthodox churches apparently consider all four prohibitions to still be in effect today. Here is a statement from an Orthodox apologetics site:
Actually – and this is not well-known – the Orthodox position is that the Apostolic Council is still binding, and this includes the prohibition on eating blood (including blood sausage, etc and strangled meats.
This prohibition on eating blood has however never been understood as a strict prohibition on the use of blood transfusions in case of medical emergency.