The best explanation I've heard for this is that these 4 things in particular were hallmarks of the pagan religions that the gentiles were coming out of. They were expected to immediatedly stop these practices and would learn the rest every sabbath day when they listened to the law of Moses being preached:
Act 15:19 Wherefore my sentence is, that we trouble not them, which from among the Gentiles are turned to God:
Act 15:20 But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood.
Act 15:21 For Moses of old time hath in every city them that preach him, being read in the synagogues every sabbath day.
BTW ET,I really enjoyed your post #310, lots of good information there.
Hi Doug. Hope you and yours are well. I always enjoy your posts as well. :)