I’m glad you recognize that we must all study for ourselves, and leave a false doctrine that doesn’t match the Bible. Saul (Paul) was well learned, and at first thought he was worshipping the correct way. But he changed as his understanding changed. Yes, we must all study for ourselves and act accordingly.
Having said that, I disagree with some statements you made. But before I get into that, I agree that we all have freewill to think for ourselves and come to our own conclusions. We must all have an open mind to consider what someone has to say, yet go by only biblical truth (not personal preference) as we know it, while respecting others rights to do the same. Keeping in mind the many false churches that have branched off of the one church that Christ started- means that the likelyhood of being raised in a false doctrine is very high.
God says to rightly divide the Word. According to my understanding through my studies, this means that what is in the Old Testament stays in the Old Testament, and what’s in the New Testament stays in the New Testament. The difference (to me) is that in the Old Testament God’s laws were obeyed physically, and God’s people were so by physical means, and that in the New Testament God’s laws are obeyed spiritually, and God’s people are so by spiritual means.
In John chapter one Jesus came to His own people, but they would not receive Him, so God switched to adoption. Now all must be born of God not by a husband’s will (not by physical means) but by spiritual means (baptism). In Romans 11 it talks about how gentiles are grafted into the vine, and how Israelites can be grafted back into their own vine. They must get baptized into Christ, just like the rest of us, in order to be God’s people once again- for God disowned them when they accepted not His one and only Son.
The Bible says that if you follow a law that you must follow all of that law. The law of Moses includes taking adulterers outside the city and stoning them to death, paying for certain things with certain animals instead of money, having a high priest sacrifice on behalf of your sins (which would be hard to find one over 2017 years old)- which would mean that you would have to undermine Christ’s sacrifice and authority- for you cannot have two ‘husbands’ at the same time- that is commiting religious adultery (Romans 7:1-4). The first authority has to die in order to ‘marry’ another. No, Christ has all authority over God’s people today (Matthew 28:18)- that leaves no authority for even Moses.