You state: So, you believe this bible passage do you? Deuteronomy 21:18-21
I believe it was true for that time. However, God created a better Way.
To reply to your idea of the Golden Rule, first we need to understand about Matthew 16:6:
"Be careful," Jesus said to them. "Be on your guard against the yeast of the Pharisees and Sadducees."
Anyone can act like a Pharisee or Sadducee. You seem to think it only applies to certain types of christians. These were people who believed they were not sinners because of their position in life. They wanted to point the finger at others as being sinners and not look inward at themselves. In other words...they were not what they preached.
They needed a Savoir just like everyone else, but they were too prideful to allow the Spirit to change their hearts, that would lead them to all Truth. They were not saved by the blood of Jesus because of their hardness of heart and their lack of faith in Jesus being who He said He was. Every sinner (that's all of us) needs the blood of Jesus to cover their sins. It's available to all but the blood does not self apply it's self to every person.
A person must apply the blood of Jesus by faith in Him. They will still fall into sin at times...it's a given. However, to be a true christian we should seek God's help to not live in sin and to always ask forgiveness for any sin we may struggle with. Always striving to be more like Jesus wanted us to be.
Matthew 23:1-39
Then Jesus said to the crowds and to his disciples, “The scribes and the Pharisees sit on Moses' seat, so practice and observe whatever they tell you—but not what they do. For they preach, but do not practice. They tie up heavy burdens, hard to bear, and lay them on people's shoulders, but they themselves are not willing to move them with their finger. They do all their deeds to be seen by others. For they make their phylacteries broad and their fringes long, ...
Matthew 7:21-23
“Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I DE CLARE to them, ‘I never knew you; depart from me, you workers of lawlessness.’
A person who knows that they sin is humble by God's standards. Satan was known to be prideful because he thought there was no need to abide by the laws of God. If one has the gift of the Holy Spirit due to faith in Christ...one only has to abide by the two laws which state.
Luke 10:27
And he answered, “You shall love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind, and your neighbor as yourself.”
John 13:34-35
A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. By this all people will know that you are my disciples, if you have love for one another.”
Now for this other scripture that you like to quote.
Matthew 7:12
“So whatever you wish that others would do to you, do also to them, for this is the Law and the Prophets
Please reread carefully. I'm having to repeat this to you once again.
This means....So whatever I wish that others would do to me, do also to them, for this is the Law and the Prophets.
If I wish that people would share with me the Truth of Jesus the Christ, then I'm going to do it to them as well. It has nothing to do with doing what the other person wants.
Do you understand how the 2 laws Jesus gave us doesn't do away with the older laws? It it perfectly self-governing. For God knows if we love Him and we love ourselves, we will want only to do the best for others, just like we want for ourselves.
Hopefully that doesn't tarnish the Golden Rule for you.