Someone asked what the issue is worshiping on Sunday instead of Sabbath/Shabbat, the issue is are we going to follow the messiah's commandment, to keep his commandments, or are we not?

John 14:15
If ye love me, keep my commandments.

It is one of the Ten Commandments also, to remember the sabbath, and keep it holy. The Catholic Church openly stated that they were changing it to Sunday as "a mark of their authority", it was also to line up with Pagan Sun worship.

Emperor Constantine decreed that the Catholic Church would adopt all Pagan traditions, and ultimately, so would Christianity in large part along with Her. The Catholic church is the whore of Babylon, we are commanded to come out from among her, not to carry on her Pagan Traditions as followers of messiah.

THESE are the commandments and judgments, which ye shall guard to do in the land, which Yahuah Elohai of your fathers gives you to possess it, all the days that ye live upon the earth. Ye shall utterly destroy all the places, wherein the nations which ye shall possess served their elohiym, upon the high mountains, and upon the hills, and under every green tree: And ye shall overthrow their altars, and break their pillars, and burn their Asherah poles with fire; and ye shall hew down graven images of their elohiym, and destroy names of them out of that place. Ye shall not do so unto Yahuah Elohaykem. DEVARIYM (Deuteronomy) 12:1-4 את CEPHER

Deuteronomy 12:2 Ye shall utterly destroy all the places, wherein the nations which ye shall possess served their gods, upon the high mountains, and upon the hills, and under every green tree:

3 And ye shall overthrow their altars, and break their pillars, and burn their groves with fire; and ye shall hew down the graven images of their gods, and destroy the names of them out of that place.

4 Ye shall not do so unto the Lord your God.

Deuteronomy 12:4

Cepher
Ye shall not do so unto Yahuah Elohaykem.

New International Version
You must not worship the LORD your God in their way.

New Living Translation
“Do not worship the LORD your God in the way these pagan peoples worship their gods.

English Standard Version
You shall not worship the LORD your God in that way.

Berean Study Bible
You shall not worship the LORD your God in this way.

King James Bible
Ye shall not do so unto the LORD your God.

New King James Version
You shall not worship the LORD your God with such things.