WHEN ROME BAPTIZED THE CALENDAR: Constantine, Imperial Christianity, and the Contested Formation of Christian Sacred Time
Keywords:
Christian holidays biblical analysis, Constantine and imperial Christianity, Origins of Christmas and Easter, Pagan traditions in Christianity, History of the Christian calendar, Biblical discernment of feast days, Halloween saints and Valentine’s DaySynopsis
Who taught Christians when and how to celebrate?
The Christian calendar often appears ancient, settled, and unquestionably sacred. Yet the observances now associated with Christianity did not emerge at one moment, from one source, or under one authority. Some practices existed before Constantine. Others developed through imperial patronage, theological calculation, missionary adaptation, medieval devotion, family tradition, commercial expansion, and modern entertainment culture.
When Rome Baptized the Calendar offers a carefully documented historical, theological, and pastoral investigation into the contested formation of Christian sacred time.
Rather than repeating the simplistic claim that Constantine invented every Christian feast, Sixbert Sangwa examines what changed when Christianity moved from a periodically persecuted faith to an imperially favoured institution. He explores how law, political power, church authority, monumental architecture, public ceremonies, social pressure, and economic interests helped transform diverse Christian practices into increasingly standardized systems of sacred time.
The book examines major observances and controversies, including:
Christmas and the disputed date of 25 December; Pascha, Passover, and Easter; Lent, Good Friday, and Holy Week; saints’ days and devotion to the dead; All Saints, All Souls, and Halloween; Valentine’s Day and the Christianization of romantic desire; and the globalization, commercialization, and digital amplification of seasonal celebrations.
This is neither an attack on the incarnation and resurrection of Jesus Christ nor a defence of every inherited tradition. The biblical events are true and foundational. The central question is whether later commemorative systems faithfully proclaim those truths or surround them with imperial interests, religious mixture, folklore, consumerism, falsehood, and rival forms of allegiance.
Grounded in Sola Scriptura and informed by primary sources, historical scholarship, archaeology, ritual studies, and contemporary cultural analysis, the book carefully distinguishes documented history from probability, disputed interpretation, and unsupported popular claims.
Its Calendar Discernment Framework helps Christians evaluate not only where a custom came from, but also what it presently teaches, whom it honours, how it forms desire, what fruit it produces, and whether Jesus Christ genuinely remains Lord of the practice.
Written for pastors, church leaders, families, students, scholars, and thoughtful believers, this book provides a biblically serious path beyond both careless conformity and fear-driven rejection. Readers are equipped to decide responsibly whether particular practices should be retained, reformed, replaced, rejected, or used as opportunities for truthful gospel witness.
Christ does not need borrowed authority from empire, commerce, folklore, or cultural tradition. He is already Lord of history, worship, conscience, and time.
References
Primary Sources and Standard Editions
Bede. (1999). The reckoning of time (F. Wallis, Trans.). Liverpool University Press.
Clement of Alexandria. (1994). Stromata. In A. Roberts & J. Donaldson (Eds.), Ante-Nicene fathers (Vol. 2). Hendrickson.
Eusebius. (1989). The history of the church from Christ to Constantine (G. A. Williamson, Trans.; A. Louth, Rev.). Penguin.
Eusebius. (1999). Life of Constantine (A. Cameron & S. G. Hall, Trans.). Oxford University Press.
Lactantius. (1984). De mortibus persecutorum (J. L. Creed, Ed. & Trans.). Clarendon Press.
Pharr, C. (Trans.). (1952). The Theodosian code and novels and the Sirmondian constitutions. Princeton University Press.
Tertullian. (1994). On idolatry. In A. Roberts & J. Donaldson (Eds.), Ante-Nicene fathers (Vol. 3). Hendrickson.
Secondary Scholarship and Contemporary Sources
Allison, D. C., Jr. (2021). The resurrection of Jesus: Apologetics, polemics, history. Bloomsbury T&T Clark.
Arnold, C. E. (1992). Powers of darkness: Principalities and powers in Paul’s letters. InterVarsity Press.
Arnold, C. E. (1997). Three crucial questions about spiritual warfare. Baker Academic.
Assmann, J. (2011). Cultural memory and early civilization: Writing, remembrance, and political imagination. Cambridge University Press. https://doi.org/10.1017/CBO9780511996306
Barnes, T. D. (1981). Constantine and Eusebius. Harvard University Press.
Barnes, T. D. (2011). Constantine: Dynasty, religion and power in the later Roman Empire. Wiley-Blackwell.
Bartlett, R. (2013). Why can the dead do such great things? Saints and worshippers from the martyrs to the Reformation. Princeton University Press.
Bayliss, R. (2004). Provincial Cilicia and the archaeology of temple conversion. Archaeopress.
Beale, G. K. (2008). We become what we worship: A biblical theology of idolatry. InterVarsity Press.
Beard, M., North, J., & Price, S. (1998). Religions of Rome (Vols. 1-2). Cambridge University Press.
Bell, C. (1992). Ritual theory, ritual practice. Oxford University Press.
Bell, C. (1997). Ritual: Perspectives and dimensions. Oxford University Press.
Blackburn, B., & Holford-Strevens, L. (1999). The Oxford companion to the year. Oxford University Press.
Block, D. I. (2014). For the glory of God: Recovering a biblical theology of worship. Baker Academic.
Bowler, G. (2005). Santa Claus: A biography. McGill-Queen’s University Press.
Bradshaw, P. F. (2002). The search for the origins of Christian worship (2nd ed.). Oxford University Press.
Bradshaw, P. F. (2020). Christmas. In T. Larsen (Ed.), The Oxford handbook of Christmas. Oxford University Press. https://doi.org/10.1093/oxfordhb/9780198831464.013.3
Bradshaw, P. F., & Johnson, M. E. (2011). The origins of feasts, fasts and seasons in early Christianity. SPCK.
Brown, P. (1981). The cult of the saints: Its rise and function in Latin Christianity. University of Chicago Press.
Brown, P. (2013). The rise of Western Christendom: Triumph and diversity, A.D. 200-1000 (10th anniversary rev. ed.). Wiley-Blackwell.
Brown, R. E. (1994). The death of the Messiah: From Gethsemane to the grave (Vols. 1-2). Doubleday.
Cameron, A. (2011). The last pagans of Rome. Oxford University Press.
Campbell, H. A., & Tsuria, R. (Eds.). (2021). Digital religion: Understanding religious practice in digital media (2nd ed.). Routledge.
Caseau, B. (2004). The fate of rural temples in late antiquity and the Christianisation of the countryside. In W. Bowden, L. Lavan, & C. Machado (Eds.), Recent research on the late antique countryside (pp. 105-144). Brill.
Chadwick, H. (1993). The early church (Rev. ed.). Penguin.
Ciampa, R. E., & Rosner, B. S. (2010). The first letter to the Corinthians. Eerdmans.
Connerton, P. (1989). How societies remember. Cambridge University Press. https://doi.org/10.1017/CBO9780511628061
Curran, J. (2000). Pagan city and Christian capital: Rome in the fourth century. Oxford University Press.
Deacy, C. (2016). Christmas as religion: Rethinking Santa, the secular, and the sacred. Oxford University Press.
Deissmann, A. (1927). Light from the ancient East (L. R. M. Strachan, Trans.). Hodder & Stoughton.
Drake, H. A. (2000). Constantine and the bishops: The politics of intolerance. Johns Hopkins University Press.
Duffy, E. (1992). The stripping of the altars: Traditional religion in England, 1400-1580. Yale University Press.
Elliott, T. G. (1996). The Christianity of Constantine the Great. University of Scranton Press.
Fee, G. D. (1987). The first epistle to the Corinthians. Eerdmans.
Ferguson, C. (2020). The twentieth and twenty-first centuries. In T. Larsen (Ed.), The Oxford handbook of Christmas (pp. 51-64). Oxford University Press. https://doi.org/10.1093/oxfordhb/9780198831464.013.6
Finegan, J. (1998). Handbook of biblical chronology (Rev. ed.). Hendrickson.
Forbes, B. D. (2007). Christmas: A candid history. University of California Press.
Forbes, B. D. (2015). America’s favorite holidays: Candid histories. University of California Press.
Geary, P. J. (1990). Furta sacra: Thefts of relics in the central Middle Ages (Rev. ed.). Princeton University Press.
Green, W. M. (1931). The Lupercalia in the fifth century. Classical Philology, 26(1), 60-69.
Hiebert, P. G. (1987). Critical contextualization. International Bulletin of Missionary Research, 11(3), 104-112. https://doi.org/10.1177/239693938701100302
Hijmans, S. E. (2003). Sol Invictus, the winter solstice, and the origins of Christmas. Mouseion, 3(3), 377-398.
Hijmans, S. E. (2009). Sol: The sun in the art and religions of Rome [Doctoral dissertation, University of Groningen]. University of Groningen Research Portal.
Hoehner, H. W. (1977). Chronological aspects of the life of Christ. Zondervan.
Holmes, M. W. (Ed.). (2007). The Apostolic Fathers: Greek texts and English translations (3rd ed.). Baker Academic.
Humphreys, C. J. (2011). The mystery of the Last Supper: Reconstructing the final days of Jesus. Cambridge University Press.
Humphreys, C. J., & Waddington, W. G. (1983). Dating the crucifixion. Nature, 306, 743-746. https://doi.org/10.1038/306743a0
Hutton, R. (1991). The pagan religions of the ancient British Isles: Their nature and legacy. Blackwell.
Hutton, R. (1996). The stations of the sun: A history of the ritual year in Britain. Oxford University Press.
Irenaeus. (1994). Against heresies. In A. Roberts & J. Donaldson (Eds.), Ante-Nicene fathers (Vol. 1). Hendrickson.
Johnson, M. E. (2012). The rites of Christian initiation: Their evolution and interpretation (2nd ed.). Liturgical Press.
Jones, C. W. (1978). Saint Nicholas of Myra, Bari, and Manhattan: Biography of a legend. University of Chicago Press.
Kelly, H. A. (1986). Chaucer and the cult of Saint Valentine. Brill.
Kelly, J. F. (2004). The origins of Christmas. Liturgical Press.
Klassen, P. E., & Scheer, M. (Eds.). (2019). The public work of Christmas: Difference and belonging in multicultural societies. McGill-Queen’s University Press.
Krautheimer, R. (1986). Early Christian and Byzantine architecture (4th ed., rev. by R. Krautheimer & S. Ćurčić). Yale University Press.
Larsen, T. (Ed.). (2020). The Oxford handbook of Christmas. Oxford University Press.
Lenski, N. (Ed.). (2012). The Cambridge companion to the age of Constantine (Rev. ed.). Cambridge University Press.
Licona, M. R. (2010). The resurrection of Jesus: A new historiographical approach. InterVarsity Press.
Lieu, S. N. C., & Montserrat, D. (Eds.). (1996). From Constantine to Julian: Pagan and Byzantine views. Routledge.
MacMullen, R. (1984). Christianizing the Roman Empire (A.D. 100-400). Yale University Press.
MacMullen, R. (1997). Christianity and paganism in the fourth to eighth centuries. Yale University Press.
Mattes, A., & Novak, C. (2025). Curating religion online: Young users’ everyday religious consumption and expression on social media. In Oxford intersections: Social media in society and culture. Oxford University Press. https://doi.org/10.1093/9780198945253.003.0041
McConville, J. G. (2002). Deuteronomy. Apollos.
McGowan, A. (2014). Ancient Christian worship: Early church practices in social, historical, and theological perspective. Baker Academic.
Miles, C. A. (1912). Christmas in ritual and tradition, Christian and pagan. T. Fisher Unwin.
Miller, D. (Ed.). (1993). Unwrapping Christmas. Oxford University Press.
Moo, D. J. (2008). The letters to the Colossians and to Philemon. Eerdmans.
Moo, D. J. (2018). The letter to the Romans (2nd ed.). Eerdmans.
Morton, L. (2012). Trick or treat: A history of Halloween. Reaktion Books.
Mosshammer, A. A. (2008). The Easter computus and the origins of the Christian era. Oxford University Press.
National Retail Federation. (2025a, September 18). NRF consumer survey finds Halloween spending to reach record $13.1 billion.
National Retail Federation. (2025b, November 6). NRF expects holiday sales to surpass $1 trillion for the first time in 2025.
National Retail Federation. (2026a, January 27). Valentine’s Day spending expected to reach new records.
National Retail Federation. (2026b, March 24). Easter spending expected to reach a record $24.9 billion.
Nissenbaum, S. (1996). The battle for Christmas. Alfred A. Knopf.
Nothaft, C. P. E. (2011). Dating the passion: The life of Jesus and the emergence of scientific chronology (200-1600). Brill.
Nothaft, C. P. E. (2018). Scandalous error: Calendar reform and calendrical astronomy in medieval Europe. Oxford University Press.
Odahl, C. M. (2010). Constantine and the Christian empire (2nd ed.). Routledge.
Origen. (1994). Homilies on Leviticus. In A. Roberts & J. Donaldson (Eds.), Ante-Nicene fathers. Hendrickson.
Oruch, J. B. (1981). St. Valentine, Chaucer, and spring in February. Speculum, 56(3), 534-565. https://doi.org/10.2307/2847741
Pohl, W., Gantner, C., & Grifoni, C. (Eds.). (2012). Transformations of Romanness: Early medieval regions and identities. De Gruyter. https://doi.org/10.1515/9783110289653
Potter, D. S. (2013). Constantine the Emperor. Oxford University Press.
Powlison, D. (1995). Power encounters: Reclaiming spiritual warfare. Baker Books.
Pye, M. (1971). Syncretism and ambiguity. Numen, 18(2), 83-93. https://doi.org/10.1163/156852771X00013
Rappaport, R. A. (1999). Ritual and religion in the making of humanity. Cambridge University Press. https://doi.org/10.1017/CBO9780511814686
Restad, P. L. (1995). Christmas in America: A history. Oxford University Press.
Rives, J. B. (2007). Religion in the Roman Empire. Blackwell.
Rogers, N. (2002). Halloween: From pagan ritual to party night. Oxford University Press.
Roll, S. K. (1995). Toward the origins of Christmas. Peeters.
Salzman, M. R. (1990). On Roman time: The Codex-Calendar of 354 and the rhythms of urban life in late antiquity. University of California Press.
Salzman, M. R. (2002). The making of a Christian aristocracy: Social and religious change in the Western Roman Empire. Harvard University Press.
Sangwa, S. (2023). Should Christians celebrate Christmas given its pagan origins? Open Christian Education Blog.
Sangwa, S. (2024). Christmas cerebration? Is the spectacle of entertainment in modern Christmas compatible with holiness? Open Christian Education Blog.
Sangwa, S. (2024). How do we count Jesus’ “three days and three nights” in the tomb? Open Christian Education Blog.
Sangwa, S. (2024). Is celebrating birthdays a pagan tradition with spiritual implications? Open Christian Education Blog.
Sangwa, S. (2024). Is it time for Christians to recognize Easter’s pagan roots? Open Christian Education Blog.
Sangwa, S. (2024). Uncovering the biblical truth behind Easter traditions: Was Jesus really crucified on Good Friday? Open Christian Education Blog.
Sangwa, S. (2024). Why should biblical Christians reconsider their participation in Christmas celebrations, given its pagan origins and spiritual undertones? Open Christian Education Blog.
Sangwa, S. (2025). Is Valentine’s Day a celebration of love or a mask for pagan traditions? Open Christian Education Blog.
Sangwa, S. (2025). Should Christians celebrate Halloween? A biblical, historical and spiritual examination. Open Christian Education Blog.
Sangwa, S. (2025). The pagan roots of Christmas: How December 25 and Roman midwinter worship shaped a Christian feast. Open Journal of Science, Philosophy & Theology, 1(2). https://doi.org/10.65655/ocp.spt.v1i2.0070
Sangwa, S. (2026). Valentine or vanity? Unmasking the ancient shadow behind the modern heart. Open Christian Education Blog.
Sangwa, S. (n.d.). How does Ash Wednesday’s historical and biblical context shape its place in Christian faith? Open Christian Education Blog.
Sangwa, S. (n.d.). What is the Holy Fire of Jerusalem: A miraculous sign of resurrection or a misunderstood tradition? Open Christian Education Blog.
Santino, J. (Ed.). (1994). Halloween and other festivals of death and life. University of Tennessee Press.
Saradi, H. (2011). The Christianization of pagan temples in the Greek hagiographical texts. In J. Hahn, S. Emmel, & U. Gotter (Eds.), From temple to church: Destruction and renewal of local cultic topography in late antiquity. Brill.
Schmalzbauer, J. (2020). Commercialism and consumerism. In T. Larsen (Ed.), The Oxford handbook of Christmas (pp. 549-559). Oxford University Press. https://doi.org/10.1093/oxfordhb/9780198831464.013.44
Schmidt, L. E. (1995). Consumer rites: The buying and selling of American holidays. Princeton University Press.
Skal, D. J. (2002). Death makes a holiday: A cultural history of Halloween. Bloomsbury.
Smith, J. K. A. (2009). Desiring the kingdom: Worship, worldview, and cultural formation. Baker Academic.
Stark, R. (1996). The rise of Christianity. Princeton University Press.
Stephenson, P. (2009). Constantine: Unconquered emperor, Christian victor. Quercus.
Talley, T. J. (1991). The origins of the liturgical year (2nd ed.). Liturgical Press.
Thiselton, A. C. (2000). The first epistle to the Corinthians. Eerdmans.
Trombley, F. R. (1993-1994). Hellenic religion and Christianization, c. 370-529 (Vols. 1-2). Brill.
Van Dam, R. (2011). Remembering Constantine at the Milvian Bridge. Cambridge University Press. https://doi.org/10.1017/CBO9780511920929
Waits, W. B. (1993). The modern Christmas in America: A cultural history of gift giving. New York University Press.
White, L. M. (1990). The social origins of Christian architecture (Vol. 1). Harvard Theological Studies.
Wilson, S. (Ed.). (1983). Saints and their cults: Studies in religious sociology, folklore and history. Cambridge University Press.
Wiseman, T. P. (1995). Remus: A Roman myth. Cambridge University Press.
Wright, N. T. (2003). The resurrection of the Son of God. SPCK.
Zerubavel, E. (1981). Hidden rhythms: Schedules and calendars in social life. University of Chicago Press.
Zerubavel, E. (2003). Time maps: Collective memory and the social shape of the past. University of Chicago Press.
