"The law was abolished" is a lie

Christians nowadays insist and are confident that Christ came to abolish the law. But if He did come to abolish the law why do they keep Sunday worship which is not even in the bible? Isn't it a little odd?

Mat 5:17 "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them."

Jesus Christ came to fulfill the law, not abolish it. He came to make it perfect so that we can receive God's blessing of the forgiveness of sins. The law of God is perfect but we are not perfect, this is why Jesus Christ had to come to change the way to worship (not the day of worship) and make so that we may be able to keep the Law of God:

Heb 8:7 "For if there had been nothing wrong with that first covenant, no place would have been sought for another. But God found fault with the people and said:
"The time is coming, declares the Lord,
when I will make a new covenant
with the house of Israel
and with the house of Judah..."

We can understand through this verse that there are "two" covenants in the bible. There is the old covenant and also the new covenant. Through the Old Covenant we can't be made perfect, this is why it is written:

Gal 3:10 "All who rely on observing the law are under a curse, for it is written: "Cursed is everyone who does not continue to do everything written in the Book of the Law."

And again in the New Testament it is also written:

James 1:25 "But the man who looks intently into the perfect law that gives freedom, and continues to do this, not forgetting what he has heard, but doing it—he will be blessed in what he does."

This is not contradicting. This is simply teaching us that through the Law of Moses we are under a curse because we can't keep it therefore fall short of God's mercy. However, since Christ came and established the perfect law, now we can receive God's blessing, perfection :) .... We need to know, the true meaning of the New Covenant. There are so many scriptures in the bible that testifies about the New Covenant. What is the real reason why God established the New Covenant? Please continue to come back for the continuation of this topic. God bless you.