SABBATH AND SUNDAY:
A brief consideration is desirable as to why and when the keeping of the seventh day as the Sabbath ceased among Christian churches. That Jesus and his disciples kept the seventh day, and without vital departures from Pharisaic usages, is indisputable. The question of Sabbath observance first became acute under Paul, with the rise of the non-Jewish Christian communities. The Petrine, or Judæo-Christian, party insisted on rigid adherence to the Jewish law. It scorned the looser practises of the converts from without Israel. To this Col. ii. 16 et seq. has reference; Paul protests against judging the piety of the neophytes "in meat, or in drink, or in respect of a feast-day . . . or a Sabbath-day" (R. V.). He protests with greater bitterness in Gal. iv. 9-11, where observance of days is denounced as a return to the "weak and beggarly elements." In Rom. xiv. 5 et seq. it is assumed that whether one day or another is distinguished, or whether all are regarded as equally sacred, is a matter of indifference: every man must decide for himself. Thus while the Petrine partizans continued to assemble for worship on the Sabbath (Acts ii. 1, iii. 1, et al.), in non-Jewish Christian circles the first day of the week came to be marked by longer worship than usual and by collections of gifts (I Cor. xvi. 2; comp. Acts xx. 7). The name κυριακὴ ἡμήρα(= "Lord's day") first occurs in Rev. i. 10, where it may mean the day of judgment (see Day of the Lord); it is next found in Ignatius, "Ad Magnesianos" (§ 9). Pliny testifies to the fact that the Christians assembled on "a fixed day" ("stato die"; "Epistolæ," x. 96).
Two Sabbaths Kept in the Second Century.The author of the "Epistle of Barnabas" adduces the occurrence of the Resurrection on the first day as the reason for the observance of this "true day" (xv.). In the meantime the attitude of the Roman authorities had become intermittently hostile to the Jews; and after the rebellion under Hadrian it became a matter of vital importance for such as were not Jews to avoid exposing themselves to suspicion (Huidekoper, "Judaism at Rome"). The observance of the Sabbath was one of the most noticeable indications of Judaism. Hence, while in the first Christian century more or less regard and tolerance for the Jewish day were shown in Rome, even by non-Jewish Christians, in the second century the contrary became the rule (Justin Martyr, "Dial. cum Tryph." ii., § 28). In the East, however, less opposition was shown to Jewish institutions. Saturday and Sunday both were celebrated by "abstaining from fasting and by standing while praying" (Rheinwald, "Archäologie," § 62), In the West, especially where Roman influence dominated, Saturday was turned into a fast-day (Huidekoper, ib. pp. 343-344). The name "Sunday" is used for the first time by Justin Martyr ("Apologies," i. 67) in accommodation to a Roman nomenclature, but with reference to the circumstances that the light was created on the first day (noticed also in the Midrash; Gen. R. iii.: "ten crowns adorned the first day") and that the "light of the world" rose from the night of the grave on the first day of the week. The Christians, accordingly, were obliged to defend themselves against the charge of worshiping the sun (Tertullian, "Apologeticus," xvi.). The celebration of two days (by the Judæo-Christians?) is attested by Eusebius ("Hist. Eccl." iii. 37) and by the "Apostolic Constitutions," which advise the keeping of Saturday as a memorial of the Creation, and of Sunday, the Lord's day, in memory of the Resurrection (ii. 59).
Originally, then, Sunday and Sabbath were kept sharply distinct. But, like the Jewish Sabbath, Sunday was deemed not merely a holiday, but a holy day, and hence fasting thereon was interdicted (Tertullian, "De Corona Militis," § 3). Ease of mind (ευφροσύνη, which corresponds to "naḥat ruaḥ"; "Epistle of Barnabas," l.c.) was the proper condition for the day. One should not kneel at prayer (Irenæus, "Fragm. de Paschate"; "Apostolic Constitutions," l.c.); the standing posture, being at first a protest against mourning and ascetic rites (such as were forbidden on the Jewish Sabbath), came to be explained as suggestive of the Resurrection. Tertullian would have all work cease on Sunday as interfering with the proper mental condition, preoccupation and worry being incompatible with joy ("De Oratione," xxiii.).
First Sunday Law, 321.Down to the sixth century the solicitude of the Church authorities was to prevent what they called the "Judaizing" of the Sunday by the rigorous prohibition of riding, cooking, etc. Even Constantine the Great, when he enacted the first Sunday law in 321, did not refer to Old Testament injunctions, but wished to have the day distinguished and kept sacred merely as the "Sun's day." This first decree was supplemented by orders concerning military exercise, but in general it affected only the courts and the markets (Eusebius, "De Vita Constantini," iv. 18-20, quoted in Herzog-Plitt, "Real-Encyc." xiv. 429). Still, such decrees virtually sanctioned the recognition of Sunday as the sole day of rest, the "Sabbath," and thus consummated the tendency that had been developing in the Christian Church for nearly two centuries to substitute the day of Jesus' resurrection for the Jewish Sabbath. In this way Sunday was given an anti-Jewish significance in accordance with Paul's contention that the Resurrection abrogated completely the old dispensation and the Law.
Jewish Attitude Toward Sunday.This aspect of Sunday has been emphasized, and with considerable force, in the discussions more or less continuously provoked in modern Jewry by the increasing neglect of Sabbath observance in the countries where the keeping of Sunday is so strongly established in industrial and social custom that the Jew has been practically compelled to follow the general usage. A few leaders (Holdheim, Samuel Hirsch) proposed to apply to this problem the principles of Reform followed in the readjustment of other religious practises to changed conditions. It is recognized that the Sabbath as the symbol of the full content of Judaism is a fundamental institution; but the argument has been advanced that astronomy discredits the assumption of a universal cosmic seventh day (comp. Judah ha-Levi, "Cuzari," ii. 20); and the notion of God's "resting" on a certain day the beginning and ending of which are determined by terrestrial phenomena, is regarded as tinged with mythology. Six days of labor are prescribed as clearly in the Sabbath law as is one day of rest; both must be religiously observed, which is impossible under prevailing conditions. Furthermore, the phraseology of the commandment does not fix the six days (the definite article is not prefixed to 
); the definite article before "seventh" implies merely that the day referred to is that following any group of six consecutive days; the phrase "the seventh day" is found also in the Pessah law (Deut. xvi. 8), where it is evident that no fixed day of the week is intended.
No obligation should be imposed that is impossible of fulfilment to the majority (B. B. 60b; Maimonides, "Yad," Mamrim, ii. 5). To the Sabbath may be applied Ps. cxix. 126, in the sense often given it (Ber. ix. 5; Yer. Ber. vii. 17; Giṭ. 60a), for now the Sabbath is "remembered," not "observed," just as Pesiḳ. R. 23 asserts is the case with non-Jews. The only consideration to be weighed is the unity of Israel. If all or most Jews were to observe Sabbath on the so-called first day in the manner in which it should be observed, namely, by abstention from work, the difficulty would be met without loss to true religion. This in substance is the contentionof Samuel Hirsch and others. Whatever may be the merits of the argument, it has had no practical result. Supplementary Sunday services have been introduced in some congregations, but the facts that Sunday has an anti-Jewish implication and that in the past many allowed themselves to be martyred for the honor of the Sabbath have never failed to arouse both the indifferent and the zealous.
