In Hebrews 8:10, the New Covenant involves God putting His law in our minds and writing it on our hearts, so the fact that the Mosaic Covenant has become obsolete does not mean that we no longer need to obey God's law. It was against God's law to commit adultery in Genesis 39:9 long before the Mosaic Covenant was made and remains against God's law after it has become obsolete, so there is nothing about any number of covenants being made or becoming obsolete that changes which laws we are obligated to follow. Unbelievers who aren't under the New Covenant still need to repent from what God's law has revealed to be sin, so not being under the Mosaic Covenant does not mean that we don't need to repent from what G od's law has revealed to be sin.
If the way to testify about God's nature were to change when the New Covenant was made, such as it becoming righteous to commit adultery or sinful to help the poor, then God's nature would not be eternal, but it is eternal, so any instructions that God gave for how to testify about His nature are eternally valid regardless of which covenant someone is under, if any. So in regard to Hebrews 7:12, the change in the law could not be referring to its content, but rather the context is speaking about the change of the priesthood, so the change in the law is in regard to its administration.
In Romans 9:30-10:4, the Israelites had a zeal for God, but it was not based on knowledge because they did not understand that the righteousness of God only comes through faith in Christ. So they failed to obtain righteousness because they pursued the Mosaic Law as through righteousness were by works in an effort to establish their own instead of pursuing the Mosaic Law as through righteousness were by faith in Christ, for Christ is the goal of the Mosaic Law for righteousness for everyone who has faith. In Romans 10:5-10, Paul quoted Deuteronomy 30:11-16, in regard to this faith saying that the Mosaic Law is not too difficult for us to obey, that the one who obeys it will obtain life by it, and in regard to what it looks like to submit to Jesus as Lord. So there is nothing in the context of this verse that even remotely suggests that Christ is ending his eternal Mosaic Law, but just the opposite.
At no point was the woman set free from needing to obey any of God's laws, so there is nothing here that leads to the conclusion that in the same way we have been set free from obeying all of God's laws. It is contradictory to think that we need to reject God's instructions for how to bear fruit for Him in order to be free to bear fruit for Him. Likewise, it is contradictory to think that the way to become unified with Christ involves rejecting what he spent his ministry teaching, especially when God's law is His instructions for how to be unified with Christ. In 1 John 2:6, it says that those who are in Christ are obligated to walk in the same way he walked, not that those who are in Christ should refuse to walk in the same way he walked.
That verse is not speaking about any laws being nailed to the cross:
1.) You shall not commit murder.
2.) This person has been found guilty of murder.
The first is an example of a law that is for our own good while the second is an example of a handwritten ordinance that was against someone that was nailed to their cross in order to announce why they were being executed. In Matthew 27:37, it says that they put the charge that was against Jesus over his head, so what was nailed to people's crosses was not the laws themselves, but the charge that was against them. This serves as a perfect analogy for the list of our violations of God's law being nailed to Christ's cross and with him dying in our place to pay the penalty for our sins, but has nothing to do with ending any of God's laws, especially because they are all eternal (Psalms 119:160). In Titus 2:14, it does not say that Jesus gave himself to end any laws, but in order to redeem us from all lawlessness, so saying that there were any laws nailed to the cross undermines what he accomplished on the cross. The Greek word "dogma" means "edict, ordinance, or decree" and is never used by the Bible to refer to God's law.
All of God's laws are eternal, so these verses should not be interpreted as referring to ending any of God's laws. God did not make any when He gave His law, so He had no need to break down His own laws. God did not give any laws for the purpose of creating a dividing wall of hostility, but rather His law instructs us to love our neighbor as ourselves. In
Matthew 5:17-19, Jesus said that he came not to abolish the Mosaic Law and warned not to relax the least part of it or teach others to do the same, so interpreting verses as speaking about abolishing any part of the Mosaic Law is calling Jesus a liar and disregarding his warning. Jesus is the exact expression of God's nature, which he testified about through living in sinless obedience to the Mosaic Law, so abolishing laws for how to testify about God's nature can't be done without also abolishing Christ.
The bottom line is that we must obey God rather than man, so we should be quicker to disregard everything that any man has said than to disregard anything that God has commanded. The authors of the Bible weren't enemies of God, so it shouldn't even make sense to you to interpret them as speaking against obeying God.
