In the 5th century, Socrates Scholasticus Church History book 5 states the fact that until Constantine imposed Dies Solis (Sungod Day) on humanity, most assemblies and believers across the world at that time still kept The Sabbath even as late as 5 centuries later after Yahshua! He clearly knew that this “Sunday” worship was based in Rome on “the account of some ancient tradition!”
"Nor is there less variation in regard to religious assemblies. For although almost all churches throughout the world celebrate the sacred mysteries 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."
It’s inaccurate to say that Emperor Constantine changed the day of worship, because we know from the writings of St. Justin Martyr, a second century apologist, that the principle day of worship for Christians in Pagan Rome was Sunday, and also from other Ante-Nicene texts.
Also, fun fact: the majority of worship services on the Sabbath are conducted by the Roman Catholic Church (all healthy priests being required to celebrate the mass on this day, and laity allowed to fill their weekly holy day of obligation by attending a service on Saturday evening instead of Sunday, and the seventh day also the most popular for devotional services such as the Rosary and the Novena) , and in Latin, the word for Saturday is “Sabato”, so the idea that they changed the Sabbath doesn’t make sense if we look at the actual liturgical texts.
For example, if we look at the Tridentine Missal, which was used by the RCC exclusively in various revisions until 1962, the calendar for Holy Week and the Saturday preceding it is as follows:
| Vespera de Tempore occurente | F.VI | | | |
| Sabbato infra Hebd Passionis Feria major | | Vespera de sequenti. | Sabb. |
| Dominica in Palmis Semiduplex Dominica I. classis | Commemoratio: S. Hermenegildi Martyris | Vespera de Officio occurente, Commemoratio Sanctorum crastinorum tantum | Dom. |
| Feria Secunda Majoris Hebdomadæ Feria privilegiata | Commemoratio: S. Justini Martyris & Ss. Tiburtii, Valeriani, et Maximi Martyrum | Vespera de Tempore occurente | F.II |
| Feria Tertia Majoris Hebdomadæ Feria privilegiata | | Vespera de Tempore occurente | F.III |
| Feria Quarta Majoris Hebdomadæ Feria privilegiata | | Vespera de Tempore occurente | F.IV |
| Feria Quinta in Cena Domini Feria privilegiata *I* | | Vespera de Tempore occurente | F.V |
| Feria Sexta in Parasceve Feria privilegiata | | Vespera de Tempore occurente | F.VI |
| Sabbato Sancto Feria privilegiata | | Vespera de sequenti. | Sabb. |
| Dominica Resurrectionis Duplex I. classis | | Vespera de Tempore occurente | Dom. |
Likewise, in the Orthodox Church, the Sabbath is a vital day of worship, not just for Vespers and All Night Vigils (which last about two hours; the liturgical day changes to the next day at the end of Vespers or a Vesperal Divine Liturgy, not the beginning, which is why you can have a Vesperal Divine Liturgy on Christmas Eve and the Holy Sabbath of Holy Week followed by the Paschal Divine Liturgy at midnight on the First Day commemorating the resurrection), but also for its significance, for on the seventh day we commemorate the repose of Christ our True God in the Tomb, after He remade us in His image on Great and Holy Friday, the sixth day (just as He made us in His image on the sixth day in Genesis).
This has an important similarity; for the only-begotten Son and Word of God, second person of the Trinity, who according to His deity is uncircumscribed and uncontainable, indeed, incomprehensible and omnipresent, was contained in the Tomb, via the important anti-Nestorian Christological principle of communicatio idiomatum, which is something we Eastern Orthodox, Oriental Orthodox and among Western Christians, Roman Catholics, Anglicans, and especially the Lutherans such as my friends
@MarkRohfrietsch @ViaCrucis and
@Ain't Zwinglian put great emphasis on.
In the Eastern Orthodox Church, and perhaps in other denominations, we draw a parallel between this and the containment of Christ our God in the womb of our Glorious Lady Theotokos and Ever-Virgin Mary, and thus she is venerated on the Sabbath in particular as a means of worshiping God and glorifying His incarnation, and in both the Eastern Orthodox and the Syriac Orthodox church, the Sabbath is also, because of its association with rest and repose, dedicated as a day of prayer for those who have reposed in the Lord, our departed loved ones. In the Byzantine Rite liturgy of Eastern Orthodoxy, this takes particular form in Soul Saturdays throughout the year, each of which are analogous to All Souls Day in the Western Rite liturgy, but distributed.
Among the ancient Eastern churches (which fall into three groups, the Oriental Orthodox, the Eastern Orthodox, and the Church of the East, which due to a schism in the 1960s is presently divided into the Assyrian Church of the East and the Ancient Church of the East), all parts of which were historically independent of Rome, and indeed until the 12th century, when the evil Muslim warlord Tamerlane began a genocide, the Church of the East was the largest in the world in terms of geographic reach, spanning an area from Socotra off the south coast of Yemen to northern Iran and eastern Turkey in the West, and from Mongolia to Tibet in the East, with churches along the Silk Road in cities such as Merv, and particular concentrations in China, India, Mesopotamia, Persia and the Levant and Socotra (of these, only those in Kerala, India, where the church was established by St. Thomas the Apostle prior to his martyrdom in 57 AD at the hands, or should I say, spear, of a local Pagan ruler, and in what is now modern day Turkey, Syria, Iraq and Iran, were spared destruction; this territory largely overlapping with the Syriac Orthodox Church, both churches using the Peshitta, the second-fourth century Aramaic translation of the Bible, and having a highly Semitic character, to this day, having vernacular Aramaic speakers (the largest surviving vernacular Aramaic speaking community consists of ethnic Assyrians in Iraq, the second largest propbably the Turoyo-speaking Syriac Orthodox and the Aramaic speaking Antiochian Orthodox (Eastern Orthodox) in Maaloula, in Syria, who suffered the desecration of the churches and abduction and imprisonment of their nuns by Al Qaeda in the 19th century).
These churches form the basis of Syriac Christianity, those churches which have used and to some extent continue to use Syriac in the liturgy, which also include the Reformed Mar Thoma Syrian Church, the Roman Catholic-affiliated Maronite Catholic Church, Chaldean Catholic Church, Syro-Malabar Catholic Church, Syriac Catholic Church and Malankara Catholic Church (all of the former having separated from the Orthodox through schisms, albeit the Maronite-Syriac Orthodox schism, unlike the others, was not the result of misguided Catholic or Protestant missionary activity but rather the result of an internal dispute, probably over Monothelitism, with the Maronites voluntarily embracing the Roman church during the Crusades as a strategic move).
Additionally, Syriac was historically used by the Eastern Orthodox Antiochian Orthodox Church, which has a special relationship with the Syriac Orthodox church closer than that of any other EO church to an OO church, so that in the territory of the Antiochian church proper (as opposed to autonomous churches associated with it in the diaspora, such as the AOCNA), in effect members of either church can receive the sacraments at the other and conversions between the two are not done, and as mentioned before, some Antiochians speak Aramaic in the vernacular (and perhaps in the liturgy in Syria; I don’t know). There have been isolated uses of Aramaic in the Eastern Orthodox Divine Liturgy in recent years, including among some Assyrians who were received into the Russian Orthodox Church around 1900.
These churches have a highly semitic character which I suspect Messianic Jews would find appealing; their music is melancholic and meilsmatic, like the best of the cantorial arts, and the liturgy solemn and beautiful. Indeed in the Church of the East, Torah portions and the corresponding Haftarah are read before the Epistle and Gospel during the Divine Liturgy, or Raza (a Syriac word meaning mystery) as they like to call it. The membership of these churches consists substantially of those of Jewish descent, some from the beginning, others over subsequent centuries; indeed in India there is a group of Syriac Orthodox Christians who are of pure Jewish descent and are endogamous, survivors of a shipwreck in the fourth or fifth century (recall that Kerala was a major trading destination for Jewish merchants after contact was solidified by Alexander the Great, the two main trading routes being to sail via the Red Sea and Socotra, Yemen, and then along the Persian Gulf and the shores of what is now Pakistan and India until arriving in the Malabar Coast, the other being a largely overland route via Edessa, the Nineveh Plains and Seleucia-Cstesiphon, with embarkation at Basra. The Kochin Jews lived in Kerala since the second century BC, but in recent years most have made Aliyah.
Also, the Ethiopian Tewahedo Orthodox Church and the Eritrean Tewahedo Orthodox Church have an extremely Semitic character, with a replica of the Ark and the Scrolls of the Law on every altar, the use of a Semitic language, Ge’ez, an Imperial family claiming plausible descent from King Solomon and the Queen of Sheba, and the country having practiced Judaism until mostly converting to Christianity in the fourth century, around the same time as Georgia. The Beta Israel (meaning House of Israel) were tolerated until the Communist Ge’ez regime took over and strangled the last Emperor in 1974 and like all Communist regimes, quickly took to anti-Semitism in order to explain its lack of success.
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Now, regarding Acts 15, what it says is that the Council of Jerusalem, as the meeting of the Holy Apostles, in particular, St. Peter, St. Paul and St. James the Just, the brother of our Lord (being according to tradition a son of St. Joseph by his deceased prior wife), determined that gentile converts did not need to be circumcised or follow certain codes of ritual purity. Whether or not one interprets this as “converting to Judaism” or not is a matter of perspective; what was enjoined in Acts 15 looks very much like the Noachide Laws in Genesis.