Really? Then how do you interpret these verses?
[Heb 8:13 KJV] 13 In that he saith, A new [covenant], he hath made the first old. Now that which decayeth and waxeth old [is] ready to vanish away.
[Heb 7:11-12, 18-19 KJV]
11 If therefore perfection were by the Levitical priesthood, (for under it the people received the law,) what further need [was there] that another priest should rise after the order of Melchisedec, and not be called after the order of Aaron?
12 For the priesthood being changed, there is made of necessity a change also of the law. ...
18 For there is verily a disannulling of the commandment going before for the weakness and unprofitableness thereof.
19 For the law made nothing perfect, but the bringing in of a better hope [did]; by the which we draw nigh unto God.
10 This is the covenant I will make with the house of Israel after that time, declares the Lord. I will put my laws in their minds and write them on their hearts. I will be their God, and they will be my people.
11 No longer will a man teach his neighbor, or a man his brother, saying, 'Know the Lord,' because they will all know me, from the least of them to the greatest.
12 For I will forgive their wickedness and will remember their sins no more."
13 By calling this covenant "new," he has made the first one obsolete; and what is obsolete and aging will soon disappear.
Heb 8:10-13
The change is given here. "my laws in their minds and write them on their hearts"
The temple was an exterior demonstration of sacrifice for sin, priests, the ceremonies. These are now fulfilled in Christ and what was external is now personal. But the principles are the same, literally, we know them in ourselves.
You can take the idea of change, and extend it incorrectly outside behaviour or the heart, and say it is all spiritual, and everything sinful is related to our physical bodies or the flesh. This is a gnostic theology. It is not what the apostles taught. They taught they knew the Lord because they found they obeyed the commandments, from their hearts.
It was the heart change is why John talks about
17 If anyone has material possessions and sees his brother in need but has no pity on him, how can the love of God be in him?
18 Dear children, let us not love with words or tongue but with actions and in truth.
1 John 3:17-18
Do I understand love? I experience love and have been changed by it and am being so. I also know defence and a closed heart, how easily I can justify everything and anything I do. So this core subject of our walk with Jesus is so hard.
Two people who are saved can take two difference emphasises and say the same thing, while thinking they disagree. Two people who are unsaved but convinced they see things as they are can argue biblical positions and be wrong because their hearts are not set in Jesus or His love. I have met both groups, and I am not able to say which is which, until you begin to talk about how to love others from our hearts. This is really the eternal perspective, and where the battle we have daily often lies.
It is like layers of reality. Each layer must be alive and working for the others to fall into place.
Am I right? In one sense we discover this as we grow in the Lord, and its reality is reality, so you do not learn it rather you find it to be so.
The apostles often wrote like this. They discovered where they were and tried to explain the theology and implications of what they found around them. So it is little wonder church life is actually so mysterious, because it is not like learning a skill, it is about becoming and walking in Jesus.
God bless you