This is not so much a commentary as it is an exploration of another way of considering the situation that is being addressed in 1 Corinthians 8.

1 Cor. 8 is often said to show that Paul taught the members of his communities that they need not observe the apostolic decree of Jerusalem described in Acts 15. While it is true Paul encountered much opposition from certain Jewish Christians who thought it is necessary to obey the Mosaic Law, and Paul and the Jerusalem apostles may have had some differences of opinion, it doesn't necessarily mean that Paul was at odds with the Jerusalem apostles over the Jerusalem decree. Though the apostles had permitted baptism of the uncircumcised, many (maybe even some of the Jerusalem apostles themselves [Gal. 2:12]) may have look upon the uncircumcised as lesser members, not acceptable for a higher office such as that of apostle.

Paul's understanding by revelation was that salvation comes through Christ apart from the Law. However, it seems unlikely Paul would have rejected the apostolic decree. These simple rules: abstaining from idol victims, blood, the stifled, and harlotry (some manuscripts also have "do not do to others what you would not want done to you"; and some omit "the stifled", possibly because it seemed redundant); are not simply Mosaic Law. Porneia or "harlotry" seems to be used to refer to various kinds of immoral sexual behavior. The abstinence from blood and stifling (or strangulation) has nothing to do with ritual purity, but rather is a safeguard to prevent animal suffering given to all nations as part of the concession to eat flesh that was given to Noah.

Idol sacrifice is a combination of superstition and animal cruelty with no redeeming value. While the Lord may have "winked" at some things the pagans did in ignorance, [Acts 17:30] idol sacrifices are simply demonic. [1 Cor 10:20] True, the Hebrews were permitted their sacrifices, and the Holy Spirit used the manner of sacrifices to point to the death of the Lord. But after the coming of Jesus, while Jewish Christians continued to respect the Temple as a "house of prayer," [Matt. 21:13] [Mark 11:17] [Luke 19:46 ] only "Israel according to the flesh" continued to eat animals that were sacrificed. [1 Cor. 10:18] Considering this, and the fact that the apostolic decree was inspired by the Holy Spirit, [Acts 15:28] it doesn't seem likely at all that Paul would have been in disagreement with the decree.

Here I give what I believe is a possible way 1 Corinthians 8 was meant by Paul to be read:

1 Now concerning the idol victims: We are aware that we all have knowledge. Knowledge puffs up, yet love builds up.

2 If anyone is presuming to know anything, he knew not as yet according as he must know.

3 Now if anyone is loving God, this one is known by Him.

4 Then, concerning the meal of the idol victims: We are aware that an idol is nothing in the world, and that there is no other God except One.

5 For even if so be that there are those being termed gods, whether in heaven or on earth, even as there are many gods and many lords,

6 nevertheless for us there is one God the Father, out of Whom all is, and we for Him, and one Lord Jesus Christ, through Whom all is, and we through Him.

7 But not in all is there the knowledge. Yet some with custom of the idol, as they eat an idol victim even their weak consciousness, is being polluted.

8 Yet food will not give us a standing with God, neither, if we should not be eating are we in want, nor if we should be eating are we satisfied.

9 Yet ye watch, lest somehow this right of yours may become a stumbling block to the weak.

10 For if anyone should be seeing you, who has knowledge, lying down in an idol's temple, will not the consciousness of him who is weak be conditioned to the eating of the idol victims? [because those considered "strong" were well instructed in the faith, they knew that attending a public event in a heathen temple where sacrifices are performed doesn't break the rule against eating idol victims. Also, they may have abstained from flesh as did those mentioned in Romans 14, and so would not be inclined to eat idol victims. However, the average Christian who ate flesh, seeing a vegetarian Christian eating fruits and vegetables in a Greek temple, would naturally sit down and eat the flesh from the animal offered to the idol.]

11 and the weak brother is perishing by your knowledge; because of whom Christ died. [It is not only whether a particular action is in itself wrong, but we should also consider if the way we behave may be a source of damage to others.]

12 Yet, likewise, ye sinning against brothers also, beating their consciousness with weakness [participle of means], ye are sinning against Christ. [Here Paul has switched from addressing those that are attending temple festivals to the the main body of the Corinthian church.]

13 Wherefore, if food is snaring my brother, I may under no circumstances be eating flesh in my lifetime, lest I should be snaring my brother. [Those who behave inconsiderately toward vegetarian Christians also sin by either tempting them with flesh food, or treating them with disregard. For this, like reclining in a temple, can be wounding. Most of what follows in 1 Cor. 9 and 10 is addressed to the average Christian, rather than those attending temple festivals].

1 Corinthians 8:1 peri de twn eidwloqutwn oidamen oti panteV gnwsin ecomen h gnwsiV fusioi h de agaph oikodomei   2 ei tiV dokei egnwkenai ti oupw egnw kaqwV dei gnwnai   3 ei de tiV agapa ton qeon outoV egnwstai up autou   4 peri thV brwsewV oun twn eidwloqutwn oidamen oti ouden eidwlon en kosmw kai oti oudeiV qeoV ei mh eiV   5 kai gar eiper eisin legomenoi qeoi eite en ouranw eite epi ghV wsper eisin qeoi polloi kai kurioi polloi   6 [all] hmin eiV qeoV o pathr ex ou ta panta kai hmeiV eiV auton kai eiV kurioV ihsouV cristoV di ou ta panta kai hmeiV di autou   7 all ouk en pasin h gnwsiV tineV de th sunhqeia ewV arti tou eidwlou wV eidwloquton esqiousin kai h suneidhsiV autwn asqenhV ousa molunetai   8 brwma de hmaV ou parasthsei tw qew oute ean mh fagwmen usteroumeqa oute ean fagwmen perisseuomen   9 blepete de mh pwV h exousia umwn auth proskomma genhtai toiV asqenesin   10 ean gar tiV idh [se] ton econta gnwsin en eidwleiw katakeimenon ouci h suneidhsiV autou asqenouV ontoV oikodomhqhsetai eiV to ta eidwloquta esqiein  11 kai apoleitai o asqenwn adelfoV epi th sh gnwsei di on cristoV apeqanen  12 outwV de amartanonteV eiV touV adelfouV kai tuptonteV autwn thn suneidhsin asqenousan eiV criston amartanete   13 dioper ei brwma skandalizei ton adelfon mou ou mh fagw krea eiV ton aiwna ina mh ton adelfon mou skandalisw

See the following related articles and commentaries:
Reflections on Romans 14
A Commentary on the Second Chapter of Colossians
When Did Animal Sacrifices Begin?