God is the same yesterday, today, and forever, so I see no particular reasons why God's commands are not for our own good in this age as well. Faith has always been an important attribute and the one and only way to become righteous has only ever been by faith, for the righteous shall live by faith (Habakkuk 2:4). In Deuteronomy 6:20-25, obeying the Law was about having faith in God to defeat Pharaoh, faith in God to bring them up out of Egypt, faith in God to bring them to the land that He promised their fathers, faith in God that His commands were for their own good, and faith in God to preserve them, so it was by faith that righteousness was theirs and by the same faith that they were careful to do all that God commanded them. As Jesus said in Matthew 23:23, faith is one of the weightier matters of the Law, so obedience to God's Law has always been about trusting Him about how we should live, and in Romans 10:5-10, it is the way to submit to Jesus as Lord.
One thing that everyone mentioned in Hebrews 11 had in common is that they all heard the voice of God and obeyed His commands by faith. This is the relationship that God wanted with Israel, but when when they heard God's voice they got cold feet and wanted to have Moses as a mediator instead (Exodus 20:19, Deuteronomy 5:22-27). Just as a marriage where the husband and wife only interacted with each other through a mediator is less than ideal, so was the the covenant that God agreed to, which is why a New Covenant was necessary. In Genesis 26:5, Abraham knew what God's commands, statutes, and laws were because he listened to God and God told him, but in working through a mediator, Moses needed to record God's laws, which was needed until Christ when he have his teachings and his example to follow for how to obey God's Law and when we have the indwelling of the Spirit to lead us in obedience to God's Law (Ezekiel 36:26-27).
Jesus fulfilled the Law in the same sense that Romans 15:18-19 says that Paul fulfilled the Gospel, namely that he fully taught obedience to it in word and in deed, not that he did away with it. The Law was given to reveal was sin is (Romans 3:20), without the Law we wouldn't even know what sin is (Romans 7:7), sin is defined as Lawlessness (1 John 3:4), and Jesus came with the message to repent from our sins for the Kingdom of God is at hand, so repenting from our disobedience to the Mosaic Law is a central part of the Gospel message. In Matthew 5:17, Jesus said he came to fulfill the law in contrast with abolishing it, yet you have interpreted it to mean the same thing. Rather, fulfilling the Law is a rabbinic term that was used to refer to interpreting it in a way that filled it up with meaning or to demonstrate a full understanding of the Law by word or by example, while abolishing the Law referred to interpreting it in a way that subtracted from its meaning or undermined it. Jesus was about to speak against what the teachers of the Law were teaching, which would have sounded to them like he was undermining the Law, so he preceded that by assuring them that he came not to undermine it, but to correctly teach how to obey it, and then proceeded to fulfill the Law six times throughout the rest of the chapter.
If you believe that Jesus was sinless, that he practiced what he preached, and preached what he practiced, then you should believe that he commanded obedience to the Law both by word and by example. In John 14:15, we are told that if we love him, then we will obey his commands, so obeying God's Law has always been about demonstrating our love for God and our faith in Him about how we should live, and thereby growing in a relationship with Messiah based on love and faith. In Romans 10:4, it is saying that a relationship with Messiah is the goal of the Law for righteousness for everyone who believes. Prior to Paul's Damascus road experience, he had been keeping the Law without having a focus on his relationship with Messiah, so he had been missing the whole point and counted it all as rubbish (Philippians 3:8). So in 2 Corinthians 3:13-16, the veil over their eyes was that they were reading the Old Covenant and missing that the whole purpose was about teachings us about Messiah and how to have a relationship with him.
In Deuteronomy 30:11-14 and Romans 10:5-10, God said that what He commanded was not too difficult and 1 John 5:3 confirms that the commands of God are not burdensome, so if Acts 15:10 we referring to the Mosaic Law, then they would be directly contradicting God, which I think is a pretty good indication that they were not speaking about the Mosaic Law. Another good indication is that the requirement being discussed in Acts 15:1 is not found anywhere in the Mosaic Law.
According to Isaiah 45:25, all Israel will be saved, so many Jews incorrectly thought that Gentiles had to become Jewish proselytes in order to become saved, which meant becoming circumcised and becoming part of the group of the people who agreed at Sinai to do everything that Moses said. By the 1st century, those who had the power passed down to them to make authoritative interpretations and rulings of the Law were referred to as sitting in Moses' seat and this had become a large body of oral laws, traditions, and fences (Matthew 23:2-4). So by agreeing to become circumcised, Gentiles were becoming Jews and agreeing to live as Jews according to all the oral laws of the Pharisees all for the purpose of becoming saved, and by rejecting this man-made requirement the Jerusalem Council was upholding God's Law.
In Matthew 15:2-3, Jesus was asked why his disciples broke the traditions of the elders and he responded by asking them why they broke the command of God for the sake of their tradition. Furthermore, he said that for the sake of their tradition they made void the Word of God (Matthew 15:6), he quoted Isaiah to say that they worshipped God in vain because they were teaching as doctrines the commands of men (Matthew 15:8-9), and he called them hypocrites for setting aside the commands of God to establish their own traditions (Mark 7:6-9). According to Deuteronomy 4:2, it is a sin to add to or subtract from God's Law, so the Pharisees needed to repent of their sin of adding their own laws, the Jerusalem Council would have needed to repent of their sin if they had told Gentiles not to follow any of God's laws. So in Matthew 23:2-4, Jesus was not criticizing the Pharisees for teaching the people to obey what God had commanded them, but rather he was criticizing them for putting the heavy burden of their many oral laws and traditions on the people. This means that in Acts 15:10, they were simply expressing the same opinion of Pharisaic oral laws as Jesus had expressed.
God has always been holy, righteous, and good, so the way to act according to God's character has existed from the beginning independently of any covenant, through it was later revealed through the Mosaic Law. So there is a difference between a set of instructions for how to act according to God's character and a covenant agreement to abide by those instructions. Anyone who wants to find out how to do what is holy, righteous, and good can do so by reading the Mosaic Law regardless of what covenant they are under, but as part of the New Covenant, we are still told to follow God's instructions for how to do what is holy, righteous, and good (1 Peter 1:13-16, 1 John 3:4-10, Ephesians 2:10).
In Hebrews 8, it says that the New Covenant was based on better promises with a superior mediator, but it does not say that it is based on superior laws because that would require following a different God with superior holiness, righteousness, and goodness. If doing a particular action was in accordance with God's righteousness before Messiah came, but after he came that is no longer the case, then God's righteousness has changed, but God's righteousness is eternal and does not change, so neither does the way to act according to it.
In Hebrews 8, God did not find fault with His law, but rather he found fault with the people for breaking His covenant because of the hardness of their hearts. God plan was not lower His righteous standard so that anyone could meet it by agreeing to a few factual statements, but rather God's plan take away our hearts of stone, give us hearts of flesh, send His Spirit to lead us in obedience to His law (Ezekiel 36:26-27), make a New Covenant where He would put his Law in our minds and write it on our hearts so that we will obey it (Jeremiah 31:33), and send His Son to redeem us from all Lawlessness (Titus 2:14) so that we would be free to obey His Law and meet its righteous requirement (Romans 8:3-4). It is those who have a carnal mind who refuse to submit to God's Law (Romans 8:7).
In Leviticus 11:44-45, it is instructing how to be holy for God is holy, so the only way for that to be abolished is for God's holiness to first be abolished. Morality is in regard to what we ought to do and we ought to obey God, so all of God's laws are inherently moral laws and it is sinful and immoral to disobey any of them.
There are many instances in Genesis where we can see that God's laws were already in place and being followed before the Law was given at Sinai. For example, with Cain and Abel, it is implied that God had given them instructions for how to make offerings, and Cain knew that he had done something wrong when he killed Abel. With Noah, he had been given instructions for what to do with clean and unclean animals, but without being told how to differentiate between the two, so the implication is that he had been given prior instructions. Likewise, he was described as being righteous and blameless in his generation (Genesis 6:9) and I don't think that was on accident, but rather because God had instructed him on what to do and he obeyed by faith.
John 8:1-12 is an example of Jesus following the law rather than making changes to how it is obeyed. There was no judge to pronounce a sentence (
Deuteronomy 19:17-21), there was no man accused (
Leviticus 20:10), he didn't have any witnesses to examine (
Numbers 35:30,
Deuteronomy 17:6,
Deuteronomy 19:5), and he did not have a confession, so if he had condemned her, then he would have acted in violation of the law. Just a few verses later Jesus said that he judged no one (
John 8:15) and he also said that he came not to judge (
John 12:47), so he did not exercise authority as a magistrate and did not condemn her, but he did recognize her action as sin, and told her to go and sin no more. The people in this passage were trying to trick Jesus into making a judgement, which he avoided doing, so he was not taking a stance against obeying his law.
I completely agree that the Law could save no one, but it was never given for that purpose. Rather, it was given as instructions for what to do by faith because we have been saved.
Paul spent a lot of time hammering home the point that obeying the Law was not about trying to become justified and that we are justified by faith apart from the Law, yet many people today are still making the error of thinking that obeying the Law was about trying to become justified, only they have compounded their error by concluding therefore our faith does away with our need to obey the Law, whereas Paul concluded that our faith does not abolish the Law, but rather our faith upholds the Law (Romans 3:27-31). The Israelites who believed God when He said that His commands were for their own good demonstrated their faith in Him about how they should live by living in obedience to them, and that is the way that our faith is to uphold the Law. We have received grace to bring about the obedience that faith requires (Romans 1:5), so our faith is no different.
The problem was not with God's law, but with the law of sin and death, so Christ gave himself to free us from the law of sin and death so that we can be free to do what is good and holy in obedience to God and in accordance with Messiah's example. Jesus did not give himself to redeem us from all Lawlessness so that we could go back to the Lawlessness that we were redeemed from, but so that we would be free to become obedient servants of God (Romans 6:16-19).
There is a theme throughout the Bible that we must obey God rather than man, so we need to be careful not to take something that was only against obeying man's laws as being against obeying the Law of the God that we serve.
While it is true that the Mosaic Law was only given to the Jews, it is not true that it was meant only for the Jews. As you noted with Isaiah 2:2-4 and with Isaiah 49:6, Israel was intended to be a light to the nations to teach them how to serve God. According to Jeremiah 31:31, the New Covenant was only made with the house of Israel and the house of Judah, so if you are not part of Israel, then you are not part of the New Covenant. However, according to Romans 9:6-8, Israel is made up of those who have faith in the promise and according to Ephesians 2:19, through faith in Messiah we are new fellow citizens of Israel, so we should follow the instructions that God gave to Israel. Every single prophet up to including Jesus came with the message to repent from our sins and to turn back to obedience to God's commands, and according to 1 Corinthians 10:1-13, we are to learn from Israel's example of disobedience, not copy it. Do you think that God is unjust and that we won't be held to account for doing the same things that the Israelites were held to account for?
I agree that we are not under the Old Covenant, but we are still under the same God, whose holiness, righteousness, and goodness don't change, so neither does the way to act according to God's character. God's character is not dependant on any covenant and does not change from covenant to covenant. Obeying the Mosaic Law is not about acting like Jews, but about acting according to the holiness, righteousness, and goodness of our God. If we do not do what God has revealed to be righteous and to go back to doing what He has revealed to be sin, then we would be undermining the righteousness of the New Covenant. According to Titus 2:11-14, our salvation involves being trained by grace to do what God has revealed to be godly, righteous, and good and to renounce doing what He has revealed to be ungodly and sinful, which is essentially what the Mosaic Law was given to instruct us how to do.
The word Greek word "ekklesia" means "assembly" or "church" was used in the Septuagint to refer to the assembly of Israel in the wildness, so that is when the Church Age began. The NT writers quoted or alluded to the OT thousands of times to show that it supported what they said and to show that they didn't deviate from it. In Acts 17:11, the Bereans were praised because they checked everything against OT Scriptures to see if what Paul said was true, so if your interpretation of Paul can't be supported by the OT, then you have understood him differently than the people who walked and talked with him. The OT is how we know we need a Messiah, how we know that there will be a Messiah, how we will know how to recognize him, how to have a relationship with him, and how we know that what the NT says about him is true, so the OT is foundational to the NT.
If you agree Christ lived in perfect obedience to the Law, that we should imitate him, follow his example, and walk in the same way that he walked, then it shouldn't be a mystery how to do that. Jesus set an example of refraining from eating pork, so straightforwardly his followers should follow his example. God gave the Law to make us conscious of sin so that we would stop doing it, not so that we would continue doing it. If we are to be overcomers, then we need to stop doing the things that God revealed to be sin, not disregard those instructions and Messiah's example of obedience to those instructions. Now that we know what God has revealed to be holy, righteous, and good and what things He revealed to be sinful, ignorance is no longer an excuse.
