The ancient churches continued to teach that the ten commandments were obligatory, fulfillable finally by the Spirit, God's way, with His righteousness given us now. The change of the day had to do with this New Way, a new way of direct relationship with God and doing His will. This historical understanding and practice, as received at the beginning, is reflected in the following current teachings:
Can you please point to the scripture that says the 4th commandment changed to this New Way you’re referencing? God made it abundantly clear not to add or subtract to His commandments. Deuteronomy 4:2 You shall not add to the word which I command you, nor take from it, that you may keep the commandments of the LORD your God which I command you.
I am not sure how one can profess to be following the will of God when not following His explicit instructions to not add or subtract from His commandments.
God said the Sabbath and His holy day is the seventh day. Exodus 20:8-11, Isaiah 58:13 so your statements appear not to reconcile with God’s Word.
2174 Jesus rose from the dead "on the first day of the week" (Mt 28:1; Mk 16:2; Lk 24:1; Jn 20:1). Because it is the "first day," the day of Christ's Resurrection recalls the first creation. Because it is the "eighth day" following the sabbath (Mk 16:1; Mt 28:1), it symbolizes the new creation ushered in by Christ's Resurrection. For Christians it has become the first of all days, the first of all feasts, the Lord's Day (he kuriake hemera, dies dominica) Sunday:
Jesus did rise the first day of the week, but there is no record that Jesus changed the Sabbath day or changed the day of worship from the seventh day to the first day.
After Jesus died there was no change to the Sabbath commandment.
Luke 23:56 Then they returned and prepared spices and fragrant oils. And they
rested on the Sabbath according to the commandment.
This is the Sabbath commandment:
Exodus 20:8 “Remember the Sabbath day, to keep it holy. 9 Six days you shall labor and do all your work, 10 but the seventh day
is the Sabbath of the Lord your God.
In it you shall do no work: you, nor your son, nor your daughter, nor your male servant, nor your female servant, nor your cattle, nor your stranger who
is within your gates. 11 For
in six days the Lord made the heavens and the earth, the sea, and all that
is in them, and rested the seventh day. Therefore the Lord blessed the Sabbath day and hallowed it.
So as you can see the Sabbath commandment did not change after the death of Christ which is why there is no such scripture in the entire bible that says the Sabbath was changed to the first day. This was all added centuries later not by the authority of God.
We all gather on the day of the sun, for it is the first day [after the Jewish sabbath, but also the first day] when God, separating matter from darkness, made the world; and on this same day Jesus Christ our Savior rose from the dead. (St. Justin, I Apol. 67G 6,429 and 432)
The Sabbath was changed outside the era of scripture in the year 300 by Constantine. There were many pagan traditions that were co-mingled with Christian teachings, one of those was the Sabbath. Sun worship became Sunday worship and slowly these and other non-Christian teachings started to be taught by the church.
The RRC admits they changed the Sabbath and not by biblical authority. Just a couple quotes of many similar. There is no scripture saying we can change anything scripture. No one has the authority to change a commandment of God written by God’s very own finger.
Q. Have you any other way of proving that the Church has power to institute festivals of precept?
A. Had she not such power, she could not have done that in which all modern religionists agree with her; —she could not have substituted the observance of Sunday the first day of the week, for the observance of Saturday the seventh day, a change for which there is no Scriptural authority.
—Rev. Stephen Keenan, A Doctrinal Catechism; New York in 1857, page 174
Question: Which is the Sabbath day?
Answer: Saturday is the Sabbath day.
Question: Why do we observe Sunday instead of Saturday?
Answer: We observe Sunday instead of Saturday because the Catholic Church transferred the solemnity from Saturday to Sunday.
—Rev. Peter Geiermann C.SS.R., The Convert’s Catechism of Catholic Doctrine, p. 50
So if one is keeping Sunday as the primary day of worship they are keeping a tradition of the Catholic Church. Jesus tells us to keep the commandments of God over the traditions of man. Matthew 15:3-9. There is no Sunday-keeping commandment, but there is for Sabbath keeping- written and spoken by God, that no man has authority over.
2176 The celebration of Sunday observes the moral commandment inscribed by nature in the human heart to render to God an outward, visible, public, and regular worship "as a sign of his universal beneficence to all."109 Sunday worship fulfills the moral command of the Old Covenant, taking up its rhythm and spirit in the weekly celebration of the Creator and Redeemer of his people.
More opinions not derived from scripture. The church can not save, the church does not have authority to forgive sins, the church does not have authority to change one of God’s Commandments and our only safeguard so we are following God is to follow His Word.
Isaiah 8:20 To the law and to the testimony! If they do not speak according to this word,
it is because
there is no light in them.
God has people in all churches and He is begging for His people to come out of Babylon Revelation 18:4, Revelation 14 and their false teachings as we are called to worship Him in Truth and Spirit. John 4:23-24