And what makes you think that because God changed the methods of punishment that all of a sudden we will no longer be punished if we disobey the laws?
See above. You simply don’t get it because you do not appreciate the distinction between a Covenant based on Law vs. a Covenant based on Love. God never changed His “methods of punishment.” As you yourself quoted from Matt. 5, the Law still stands and the prescribed punishment of the Law are still applicable for those who are under the law. But, Christians are not under the Law. Yet, you keep assuming (very wrongly) that you are responsible for obey the Mosaic Law - that you are responsible to God on the basis of law. You are not. You are only responsible to the Person of Jesus Christ.
When you can appreciate this very real distinction, then you will see why you are contradicting your own professed beliefs by maintaining that you are bound to the Saturday Sabbath. If you are not bound to the Law (which you are not if you are a Christian), then you are not bound to any of the prescriptions of the Law.
Ergo, you may keep the Sabbath on any day you please. And the early Church chose, as a matter of custom and its Divine authority, to keep in on Sunday, the day that Christ rose.
Those who do not repent of their SINS (remember, sin is transgressing the law of God)
Wrong. Sins are an offense against the righteous Person of God.
WILL be punished by not entering into heaven.
Siiiggghhh.

But, they will not be punished for the sake of violating a Law, since they did not break a Covenant of Law, but rather (by their sins) they violated a Covenant of Love! If adultery were not considered to be against any civil law, it would still be a violation of a covenant of love between a man and his wife. It would still act to separate and sow division between the man and his wife. The same is true of Christ and a Christian when a Christian sins. A sinful Christian (who does not repent) will go to hell, not because he violated any law, but because He divided Himself from the Person of Christ, Who is righteous and the only source of eternal life.
So, there is no legal dynamic at play here at all. Sin, for a Christian, is not the violation of any Divine Law, since the Christian is not bound to God by a Covenant of Law, and so not obligated to obey any Law. Rather, they are obligated to love and be faithful to the Person of Jesus Christ. If they go to hell, it is because they have separated themselves from their loving intimacy (a loving Covenant) with Christ, not because they violated any Law. Is this so hard to understand?

I am calling you to consistency in your theology. Right now, your theology is very inconsistent and confused.
Does that mean that their salvation hinges on whether or not the keep the law legalistically? NO, for we are saved by grace.
You cannot have it both ways. If we are saved by grace (that is, a Covenant of Love), then we are not bound to the Law at all.
A pear tree does not produce pears to prove that it is a pear tree, it produces pears BECAUSE it IS a pear tree. True faith will cause obedience.
Yes. But not obedience to law. That’s the point. Rather, we show obedience to a Person, i.e., loving fidelity to Jesus Christ, as so we act in righteousness by acting like Him. This is the distinction which you are not appreciating.
No, that’s called changing a commandment that God has set up as a means of knowing what we are doing wrong.

And why can’t the Church change something IF we are not bound by or under the Law??? It most certainly can because we are not bound by any Law. This, again, is the point. When you speak of “changing a commandment,” you mean the changing of a law. But, we are not bound by any Law, and so we are not “changing” anything.

Rather, we are taking what we are bound by (the Righteousness behind the Law) and applying it to a new situation - via the Church’s Christ-given authority to “bind and loosen” (Matt 16:19 & 18:18, etc.). So, again, you simply don’t get it. You are very short-sighted in your theology, and you contradict yourself. You need to step back and look at what you’re really saying in order to see this. We are not bound by any Law. You need to come to terms with that.
“Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven.” – Matthew 5:19
You, again, wrench Matt. 5 out of its intended context. Jesus is speaking to Jews (or Jewish Christians who observed the Law), and He is saying that the Law will remain in force for Jews …which is true. It is still in force for Jews today. But, it is not in force for those who do not live under the Law. So, unless you wish to live under the Law, then you are not bound by any of the prescriptions of the Mosaic Law. Yet, if you do wish to be bound by any of the prescriptions of the Mosaic Law (e.g. the Saturday sabbath), then you must keep the entire Law …or else you yourself are subject to the censure of Jesus presented above. Do you the problem now??
continued. . .