Isaiah 66:23

This phrase, along with 'from sabbath to sabbath', indicates regular and continuous periodicity. New moons were important festivals in the Israelite calendar (Numbers 28:11-15). The use here is not to establish a law, but to describe the *frequency* and *regularity* of worship in the eschatological age, using familiar terms from the Old Covenant worship system.

Similar to 'new moon', the Sabbath was the central day of rest and worship in the Old Covenant. Here it functions as a temporal marker that underscores the uninterrupted and universal nature of future worship. It is not a prescription for the literal observance of the Mosaic Sabbath for 'all flesh', but a rhetorical figure for constant and universal worship.

This phrase emphasizes the universality of worship in the eschatological age. It is not limited to Israel but includes all nations, which is a recurring theme in Isaiah (Isaiah 2:2-4, 49:6). The inclusion of 'all flesh' is key to understanding that worship transcends the particularities of the Mosaic covenant.

The verb describes the general act of worship and reverence. It does not specify Old Covenant rituals or forms of worship, but the fundamental act of bowing down before God. This reinforces the idea that the emphasis is on the *attitude* and *regularity* of universal worship, not on the *observance* of specific ceremonial laws.

Patristic

The Church Fathers broadly debated the significance of the ceremonial laws of the Old Testament in relation to the Christian era. Justin Martyr (c. 100-165 AD) in his *Dialogue with Trypho* (chaps. 12-29) argued that the literal observance of the Sabbath was not binding on Gentile Christians, viewing the Sabbath as pointing toward a spiritual rest in Christ. However, Justin does not directly cite Isaiah 66:23 in that context; rather, he interprets Isaiah chapter 66 as a prophecy of the universal calling of the Gentiles to true worship. Irenaeus of Lyon (c. 130-202 AD), in his *Adversus Haereses* (IV, 8-9), developed the idea that ceremonial laws, including the Sabbath, were temporary figures that found their fulfillment in Christ. Origen (c. 184-253 AD), in his *Homilies on Isaiah* and in *De Principiis* (II, 11), interpreted the mention of 'all flesh' in Isaiah 66:23 as a reference to universal and eschatological worship, not confined to a specific day. This interpretive current sees in the passage a prophecy of spiritual and continuous worship in the messianic era, not reducible to the observance of a specific weekly day.

Reformed

Reformed theology interprets Isaiah 66:23 through the lens of covenant theology, distinguishing between the Mosaic covenant (with its ceremonial and civil laws) and the new covenant in Christ. References to the Sabbath and new moons are seen as shadows or types that find their fulfillment in Christ and New Covenant worship. The verse predicts universal and continuous worship, but not the re-establishment of Jewish ceremonial practices. The principle of 'Sabbath rest' is maintained, but its form and specific day are transformed in the New Covenant, focusing on rest in Christ and regular worship without ties to a specific day of the week.

Interpretive tension: Within the Reformed system, tension can arise when trying to balance the continuity of the Sabbath principle (rest and worship) with the discontinuity of its literal Old Covenant observance, especially in how the 'Lord's Day' (Sunday) is applied in relation to the biblical Sabbath. Isaiah's text does not directly resolve this tension, but frames it in an eschatological context.

Arminian

The Arminian tradition, like the Reformed, emphasizes the believer's freedom from the yoke of Old Covenant ceremonial law. Isaiah 66:23 is interpreted as a promise of universal worship in the coming age, where God's grace enables 'all flesh' to respond in worship. References to 'Sabbath' and 'new moon' are understood as expressions of the regularity and totality of worship, not as mandates for literal observance. Salvation by grace through faith is central, and the observance of specific days is not a requirement for justification or sanctification.

Interpretive tension: For Arminianism, tension might arise in how the universality of 'all flesh' coming to worship relates to individual freedom of choice. While the text affirms the divine purpose of universal worship, the mechanics of how 'all flesh' comes to worship without coercion, while maintaining human agency, is an inference that the text does not explicitly detail.

Contemporary

Contemporary scholars like N.T. Wright emphasize the continuity and discontinuity between covenants. Isaiah 66:23 is seen as part of the 'new creation' vision, where old categories are transformed and fulfilled in Christ. Future worship is universal and constant, but not governed by the shadows of the Old Covenant. The temporal markers are metaphors for uninterrupted and global worship. Others, like Gordon Fee, emphasize that the New Testament frees believers from the observance of specific days, making the literal application of this verse anachronistic for the church.