Here are some interesting historical references you might find interesting that clear up a few misconception people may have about Sunday worship entering the Roman empire and the early Church....
Historically, Constantine did not change the day of worship as many claim. According to the historical records, Constantine made a civil Sunday law that the Roman Catholic Church adopted in order to practice and promote Sunday worship over the Sabbath of God's 4th commandment...
First Sunday Law enacted by Emperor Constantine - March, 321 A.D.
“On the venerable Day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed. In the country, however, persons engaged in agriculture may freely and lawfully continue their pursuits; because it often happens that another day is not so suitable for grain-sowing or for vine-planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost. (Given the 7th day of March, Crispus and Constantine being consuls each of them for the second time [A.D. 321].)” Source: Codex Justinianus, lib. 3, tit. 12, 3; trans. in Philip Schaff, History of the Christian Church, Vol.3 (5th ed.; New York: Scribner, 1902), p.380, note 1.
Now a professed Christian, Constantine nevertheless remained a devout sun worshipper. “The sun was universally celebrated as the invincible guide and protector of Constantine,” notes Edward Gibbon in his classic Decline and Fall of the Roman Empire, ch. xx, par. 3.
Constantine even printed coins which “bore on the one side the letters of the name of Christ, on the other the figure of the sun god.” Arthur P. Stanley, History of the Eastern Church, lect. vi, par. 14.
Again, Constantine’s promotion of Sunday observance was part of his definite strategy to combine paganism with Christianity: “The retention of the old pagan name of dies Solis, or 'Sunday,' for the weekly Christian festival, is in great measure owing to the union of pagan and Christian sentiment with which the first day of the week was recommended by Constantine to his subjects, pagan and Christian alike, as the ‘venerable day of the Sun.’” – Stanley’s History of the Eastern Church, p. 184.
In spite of the rising popularity of Sunday sacredness, Church historian Socrates Scholasticus (5th century) wrote: “For although almost all churches throughout the world celebrate the sacred mysteries [of the Lord's Supper] on the Sabbath of every week, yet the Christians of Alexandria and at Rome, on account of some ancient tradition, have ceased to do this.” – Socrates Scholasticus, Ecclesiastical History, Book 5, ch. 22.
Another historian also confirmed this by stating, “The people of Constantinople, and almost everywhere, assemble together on the Sabbath, as well as on the first day of the week, which custom is never observed at Rome or at Alexandria.” – Sozomen, Ecclesiastical History, Book 7, ch. 19. Thus even in the 5th century, Sabbath keeping was universally prevalent (except in Rome and Alexandria) along with Sunday keeping. Many Christians kept both days, but as the centuries wore on, Sunday keeping grew in prominence and especially within Roman Catholic territories.
In 330 A.D., Constantine moved his capital from Rome to Constantinople (modern Istanbul), thus preparing the way for the Roman Catholic Popes to reign in Rome as the successors of Constantine. As the Papal Church grew in power, it opposed Sabbath observance in favour of Sunday sacredness and made the day change official in the Council of Laodicea (A.D. 363-364). Constantine's law had now been fully integrated into the Papal Church and the final step of the Sabbath to Sunday change was complete.
So around the year A.D. 364, the Catholic Church outlawed Sabbath keeping in the Council of Laodicea when they decreed 59 Canon laws. The following is the relevant Canon law: Canon XXIX: “Christians must not judaize by resting on the Sabbath, but must work on that day, rather honouring the Lord's Day; and, if they can, resting then as Christians. But if any shall be found to be judaizers, let them be anathema from Christ.” (Percival Translation).
Four hundred years after the death of Christ and one hundred years after Constantine's linking of Church and State by his Sunday law edict, Rome and Alexandria were the only places in the world where many of the Christians kept only Sunday and not the true Sabbath. Why was it that Rome and Alexandria were also the first locations that Sunday worship began? Because this is where the pagan practices of Babylon eventually landed after it was conquered. And what was the dominant pagan practice that the Babylonian priests brought with them? Sun worship which was done on Sun-day! See the history of Sunday worship for more detail.
So one can understand why Rome and Alexandria did not bother to keep the true Sabbath as they had not done so for 200 years. Throughout the entire history of the changeover from Sabbath to Sunday, Rome and Alexandria had worked together. Alexandria provided the philosophical reasons for the changes and Rome provided the decrees and anathemas. Constantine's help was given only to the worldly Church leaders at Rome and those Christians that resisted the errors that were being introduced into the Church met with his opposition. “Unite with the bishop of Rome or be destroyed,” was Constantine's position.
“Great as were the favors which Constantine showed to the church, they were only for that strong, close-knit, hierarchically organized portion that called itself Catholic. The various [so-called] heretical sects could look for no bounty from his hands.” – Williston Walker, A History of the Christian Church, page 105.
The change of the Sabbath to Sunday was totally completed by the seventh century as the Popes consolidating their enormous power persecuted all who resisted their innovations. Did Satan use Constantine to play a key part in his plan to change the Sabbath to his day being Sunday? The answer is clear! From sun worship 2000 B.C., to Sunday worship in the Church. Satan infiltrated the Christian Church and most are oblivious to the fact that this has happened or understand the relevance. Sunday or “dies solis”, the day of the sun came from Satan worship and is his day. (more from here).
God bless
Sylvester I changed it:
https://ia904602.us.archive.org/17/items/pope-sylvester-and-melanchthon-quotes-image/Pope%20Sylvester%20And%20Melanchthon%20Quotes%20Image.png
Roman Catholicism:
‘Pope’ Sylvester I (Pope Sylvester I (also Silvester, 285 – 31 December 335) was the bishop of Rome from 31 January 314 until his death.) - CATHOLIC ENCYCLOPEDIA: Pope Sylvester I - https://www.newadvent.org/cathen/14370a.htm
[Latin] “... Similiter et feriae a fando dicuntur, ob quam causam Silvester papa primus apud Romanos constituit ut dierum nomina quae antea secundum nomina deorum suorum vocabant, id est, Solis, Lunae, Martis, Mercurii, Veneris, Saturni, feria deinceps vocarent, id est, prima feria, secunda feria, tertia feria, quarta feria, quinta feria, sexta feria, quia in principio Genesis scriptum est quod Deus per singulos dies dixerit : prima, Fiat Lux; secunda, Fiat firmamentum; tertia, Producat terra herbam virentem, similiter, etc. Sabbatum autem antiquo legis vocabulo vocare praecepit, et primam feriam diem Dominicam, eo quod Dominus in illa resurrexit. Statuit autem idem papa ut otium sabbati magis in diem Dominicam transferretur, ut ea die a terrenis operibus ad laudandum Deum vacaremus, justa illud quod scriptum est : Vacate et videte, quoniam ego sum Deus (Psal. XLV). ...” - Beati Rabani Mauri, Fuldensis Abbatis et Moguntini Archiepiscopi, de Clericorum Institutione, ad Heistulphum Archiepiscopum; Libri Tres. (Anno 819.) Ad Fratres Fuldenses Epigramma Ejusdem; Liber Secundus, Caput XLVI. Column 361 (Left; PDF page 35) - http://www.documentacatholicaomnia.eu/02m/0788-0856,_Rabanus_Maurus,_De_Clericorum_Institutione_Ad_Heistulphum_Archiepiscopum_Libri_Tres,_MLT.pdf
[Translated English] “... Pope Sylvester, first among the Romans, ordered that the names of the days [of the week], which they previously called after the name of their gods, that is, [the day] of the Sun, [the day] of the Moon, [the day] of Mars, [the day] of Mercury, [the day] of Jupiter, [the day] of Venus, [the day] of Saturn, they should call feriae thereafter, that is the first feria, the second feria, the third feria, the fourth feria, the fifth feria, the sixth feria, because that in the beginning of Genesis it is written that God said concerning each day: on the first, "Let there be light:; on the second, "Let there be a firmament"; on the third, "Let the earth bring forth verdure"; etc. But he [‘Pope’ Sylvester I] ordered [them] to call the Sabbath by the ancient term of the law, [to call] the first feria the "Lord's day," because on it the Lord rose [from the dead], Moreover, the same pope decreed that the rest of the Sabbath should be transferred rather to the [counterfeit] Lord's day [Sunday; the real “Lord’s day” (Revelation 1:10) is the 7th day the Sabbath of the LORD], in order that on that day we should rest from worldly works for the praise of God.7 ...” - Exactly Which Pope Changed The Sabbath To Sunday? - http://www.aloha.net/~mikesch/sylvester-I.htm
“...But the [Roman Catholic] Church of God has in her wisdom ordained that the celebration of the Sabbath should be transferred to “the [counterfeit] Lord's day:” …” [The Catechism of the Council of Trent; On The Third Commandment; pg 267] - The catechism of the Council of Trent : Catholic Church : Free Download, Borrow, and Streaming : Internet Archive - https://www.archive.org/stream/thecatechismofth00donouoft#page/n271/mode/2up/search/sabbath
“… the Sabbath … this commandment, … is not fixed and unalterable, but is susceptible of change … ” [The Catechism of the Council of Trent published by command of Pope Pius The Fifth, translated into English by the Rev. J. Donovon, Professor, &c Royal College, Maynooth; Baltimore: Published by Lucas Brothers. No. 170 Market Street; Printed By James Young, Baltimore; On The Third Commandment; pg 264] - The catechism of the Council of Trent : Catholic Church : Free Download, Borrow, and Streaming : Internet Archive - https://www.archive.org/stream/thecatechismofth00donouoft#page/n269/mode/2up/search/sabbath
Protestants:
Philip Melanchthon ( Philip Melanchthon - Wikipedia ) on Daniel 7:25 -
[Old English] “... But what meaneth the aungell to saye: He shall s•arle or destroye ye hyghe sayn∣tis? verely els but that with his false doctryne capciouse othes articles / & in∣terrogacions he shall fraudelently de∣ceyue and trappe the simple innocents and shed their blode tyrannously. Also he shall arrogantly take vpon him & thin∣ke to change the state of tymes and la∣wes. He weneth to change ye tyme which with swerde and fyer thinketh to shorten the lyfe of man and to preuent and disa∣point gods infallible eternall and immu∣table prouidēce wherby he hath prefiyed euery manis tyme & houre of deth which as noman can differre or prolong it / so cā∣ne noman shorten nor preuent it / except men will make God an ignorant persone and so consequently no god at all. He chā∣geth the tymes and lawes that any of the [page 118-119] sixe worke dayes commanded of god will make them vnholy and idle dayes when he lyste / or of their owne holy dayes abo∣lisshed / make* worke dayes agen / & when they changed ye Saterday into Sondaye / of eting dayes fasting dayes / of mery and glad dayes to marye in / they can make so∣rowfull dayes forbiddinge maryages. They haue changed gods lawes and tur∣ned them into their owne tradiciōs to be kept aboue Gods preceptis. And as for their owne lawes they will change & bre∣ke them when they lyste. And this powr shal anticrist haue whether it be for long or shorte tyme. For so miche sowneth the Hebrew phrase / which is for a tyme / a lyt∣le whyle / & half a tyme / signifyinge that Anticryst shall make lawes to stande as long and as shorte tyme as he listeth and the tymes will he order / sett and change at his owne plesur. But is it not onely ye office of god to chang tymes and lawes? Here is therfore the prophecye fulfylled of him. Euen to exalt himselfe aboue all thing that god is called. This text. But the hyghe saynts he shall tangle trappe & destroye and arrogantly thinke to chan∣ge the tymes and lawes &c. is of diuerse lerned men diuersely translated. ...” - (The Exposicion of Daniel the Prophete Gathered oute of Philip Melanchton, Johan Ecolampadius, Chonrade Pellicane [and] out of Johan Draconite (1545); page 118-119) - The exposicion of Daniel the prophete gathered oute of Philip Melanchton, Iohan Ecolampadius, Chonrade Pellicane [and] out of Iohan Draconite. [et] c. By George Ioye. A prophecye diligently to be noted of al emprowrs [and] kinges in these laste dayes - https://quod.lib.umich.edu/e/eebo/A04696.0001.001/1:11?rgn=div1;view=fulltext
The Exposicion of Daniel the Prophete Gathered oute of Philip Melanchton, Johan Ecolampadius, Chonrade Pellicane [and] out of Johan Draconite (1545) : MVT : Free Download, Borrow, and Streaming : Internet Archive - https://archive.org/details/TheExposicionOfDanielThePropheteGatheredOuteOfPhilipMelanchtonJohan/page/n118/mode/1up
The Exposicion of Daniel the Prophete Gathered oute of Philip Melanchton, Johan Ecolampadius, Chonrade Pellicane [and] out of Johan Draconite (1545) : MVT : Free Download, Borrow, and Streaming : Internet Archive - https://archive.org/details/TheExposicionOfDanielThePropheteGatheredOuteOfPhilipMelanchtonJohan/page/n119/mode/1up
[Modern English] “… But what does the angel (Gabriel) mean to say: He shall wear out (persecute) or destroy the high (heavenly) saints (holy persons) (Daniel 7:25)? Verily (truly) (what) else (is it) but that with his false doctrine and capricious (unaccountable changes of) other articles (of faith & practice) & (with) interrogations (subtle questionings) he shall fraudulently deceive and trap the simple innocents and shed their blood, tyrannously. Also he shall arrogantly take upon him(self) and think to change the state of times and laws. He thinks to change the time, which with (the) fire and sword (of persecution), thinks to shorten the life of man(kind) and to prevent and disappoint God’s infallible, eternal and immutable providence whereby he (God) has prefixed every man’s time and hour of death which no man (anyone of mankind) can defer (delay) or prolong (extend) it, so can no man (anyone of mankind) shorten, nor prevent it, except men (anyone of mankind) will make God an ignorant person and so consequently no ‘God’ at all. He changes the times and laws that any of the [page 118-119] six work days commanded of God will make them unholy and idle days when he wills (desires by reason, “thinks”), or of their own ‘holy days’ (liturgical festal calendar days, like ‘lent’, &c) abolished, make work days again, and when they changed the Saturday (the 7th Day of the week in common, not technicality, as the days of God, are sunset to sunset (“even unto even”), not midnight to midnight (Roman times)) into Sunday (the 1st day of the week in common, not technicality), of eating (feasting) days (and) fasting days, of merry (celebratory) and glad days to marry in, they can make sorrowful days (even) forbidding marriages (1 Timothy 4:3). They have changed God’s laws and turned them into their own traditions to be kept above God’s precepts. And as for their own laws, they will change and break them when they will (desire by reason, “thinks”). And this power (authority) shall Anti-Christ (Latin: Vicarius Christi; koine Greek: Anti Christos) have, whether it be for (a) long or (a) short time. For so much shows (reveals) the Hebrew phrase, which is for a time, a little while (times), and a half a time, signifying that Anti-Christ shall make laws to stand as long and as short (of) time as he wills (desires by reason, “thinks”), and the times will he order, set and change at his own pleasure. But is it not only the office (position and prerogative) of God to change times and laws (Daniel 2:21; Acts 17:26)? Here is therefore the prophecy fulfilled of him (Anti-Christ). Even to exalt himself above everything that God is called (Daniel 11:36; 2 Thessalonians 2:4). This text, But the high (heavenly) saints (holy persons) he (Anti-Christ) shall tangle (ensnare), trap and destroy, and arrogantly think to change the times and laws, etc.; is of diverse (differing) men diversely (differently) translated. …”
William Ambrose Spicer (SDA, 1918), Our day in the light of prophecy and providence, page 154 - Our day in the light of prophecy and providence : Spicer, William Ambrose, 1866- : Free Download, Borrow, and Streaming : Internet Archive - https://archive.org/details/ourdayinlightofp00spic/page/154/mode/1up
Stephen Bohr (SDA), Studies On Daniel (PDF), page 175 - http://secretsunsealed.org/content/PDF_downloads/All
Roy Allen Anderson (SDA), Unveiling Daniel And Revelation, page 95 - Unveiling Daniel and Revelation - https://books.google.as/books?id=ABuq_yAvNhkC&dq=Roy+Allen+Anderson+Phillip+Melanchthon&focus=searchwithinvolume&q=Roy+Allen+Anderson+Phillip+Melanchthon