There are two questions here that are quite independent that should be the subject of separate question but I will take them one at a time here.
The verb δοκέω (dokeó)
In Acts 15:28 this verb is part of the phrase, ἔδοξεν γὰρ τῷ Πνεύματι τῷ Ἁγίῳ καὶ ἡμῖν … = "For it has seemed good to the Holy Spirit and to us … " BDAG defines this useage (#2 b β) as:
to appear to one's understanding, seem, be recognized as … impersonal: it seems to me, … it seems best to me, I decide, I
resolve, eg, Luke 1:13, Acts 15:22, 25, 28.
The phrase here, "it seemed best to the Holy Spirit" is a classic anthropomorphism applied to a member of the Godhead and is a quintessential "Lukism" saying that this is what the meeting perceived the Holy Spirit was leading them to decide. (I wish more church councils would operate this way and save much heartache!)
Does this mean "Is there uncertainty?" If this were merely humans forming an opinion, then the result would be quite uncertain as with all human endeavour. However, here we are discussing the opinion of the Holy Spirit of God who is omniscient and reveals the mind of God (1 Cor 2:10, 11). Thus, when the Holy Spirit reveals something based on the opinion of God (as it necessarily is) then the result is quite certain.
Should we avoid eating steak rare?
I will not answer this question as it is a matter of personal ethics. However, I will set out what the Bible says on this controversial topic.
Of the half dozen covenants made by God with various groups of people in the Old Testament, a few contain this same requirement:
- Under the Noahide covenant (Gen 8:20 - 9:17), made will all mankind (Gen 9:8-10, 16, 17), one of the requirements was a prohibition against eating any blood, Gen 9:4.
- Under the Israelite covenant (Ex 19-24, Parts of Leviticus, Numbers and Deuteronomy) one of the prohibitions was eating blood, Lev 3:17, 7:26, 27, Lev 10:18, 17:10, 13, 14, 19:26, Num 23:24, Deut 12:23-27, 15:23, etc. See also Eze 18:6, 15, 33:25. Note that this requirement specifically applied also to foreigners as well Lev 17:10-13, etc.
There is much debate about what the "New Covenant" (Matt 26:28, Mark 14:24, Luke 22:20, 1 Cor 11:25, 2 Cor 3:6, Heb 8:6-13, 9:15, 10:16, 29, 12:24) actually means and what it entails, that I will not debate here. All that is necessary is to observe that the resolution of the Jerusalem council reached a decision prompted by the Holy Spirit about a contentious subject (the status of the Mosaic Law, specifically circumcision) and then set out four requirements that come from the Torah and the Noahide covenant:
- abstain from food scarified to idols
- abstain from eating blood
- abstain from the meat of strangled animals (presumably because it contained blood)
- abstain from sexual immorality
It is interesting that in the history of the church, all these requirements have enjoyed a very chequered "observance" - sometimes being observed faithfully and other times ignored completely. Even the instruction to abstain from sexual immorality has notoriously often been observed in the breach resulting in numerous church official "mea culpas" over child abuse perpetrated by clergy and elders, to name just one example.