The way one properly forms their conscience is through scripture and apostolic tradition.
The earliest first century Gentile followers of Jesus didn’t have scripture or apostolic tradition. I disagree with what you said above. Wholeheartedly. It’s a completely legalistic viewpoint that you present. If you’re comfortable within those confines (legalism) then have at it.
Yes, they had both. They had the Old Testament, the letters started coming in within 10 or 20 years and, better than those, they had the personal testimony of the Apostles and disciples. The earliest Gentile followers were even brought into the synagogues located beyond Israel at first. If you read the Bible, you'd know this.
My view is not legalistic, and I'll explain why (again). Legalism means the law is an end in itself. Follow the law to the letter, then no matter what your interior is like, you are justified. Non-legalism means that the law is an illumination, a guide for the just and to maintain order among the unjust.
I know you will never be convinced of anything happening outside your head. That may work for you (I doubt it), but it's not viable for future generations.
