From the early centuries, Christian worship has seen a continuous process of development and change in response to theological and cultural factors. Although the basic elements-the service of the Word and of the Lord's Table-have remained constant, their shape and setting have undergone modification from century to century, from region to region, and from Christian community to community within both the Eastern and Western branches of the church. The result of this process is the great variety of liturgical forms through which Christians worship the Lord across the world today. These entries begin with a survey of the evidence for Christian worship in the earliest centuries. This is followed by a description of the liturgical traditions of the Eastern churches and a discussion of the various regional rites of the Western (Catholic) church that culminated with the establishment of liturgy uniformity at the Council of Trent. Discussion of the worship in movements of the Protestant Reformation is followed by a survey of worship in the major movements and denominations that developed in the post-Reformation era. The section concludes by considering the impact of twentieth-century renewal movements on Christian liturgy. Our sources for the study of Christian worship in the early post-biblical period are not liturgical texts, such as missals or prayer books, or systematic treatments by theologians of the era. Instead, these sources usually make incidental references to Christian liturgy in writings devoted to other purposes, such as the defense of the Christian faith against pagan opposition, the refutation of false teachings within the Christian community, and the instruction of the faithful in scriptural exposition and sermons. It would be a mistake, however, to infer from the nature of our sources that the church's liturgical practices during this period were informal, undeveloped, and without consistency. Even the documents of the New Testament reveal a worshiping community that practiced baptism and eucharistic celebration, and mention of these practices occur in the writings of the fathers of the church through the following centuries. The existence of the worshiping community is an underlying datum in this patristic literature, the ongoing evidence of the creation of a new covenant people through the death and resurrection of Christ, and the continued operation of the Holy Spirit to establish the Kingdom of God.
The liturgical traditions of the East (the Orthodox churches) are rich and varied. Although these traditions derived from common roots shared by several prominent ancient churches, they developed distinctive theological emphases and spirituality. God was seen as the distant and holy Other, yet also as the One "made flesh" who "dwelt among us. " The liturgy reflected other contrasts. Worshipers were invited to participate in the heavenly mysteries, but they were also reminded that they were unworthy to approach them; they rejoiced in the triumph of Christ, but also expressed a patient endurance until the day when that victory would be fully revealed; they stood erect before the majesty of God, but also bowed in humility and awed adoration. As these six entries demonstrate, the Eastern traditions emphasizes the divine Mystery of God the Creator, of Christ the Redeemer, of the Spirit the sanctifier, in a colorful and many-faceted manifestation.
The Roman rite was only one of several rites that existed in the Western church prior to the time of the Reformation, as shown in these eight entries. As the Roman rite gained influence, the traditions of other regions became assimilated to it. Some of the regional rites, however, retained a distinctive character up to the Reformation era. In the Council of Trent, Catholic liturgy was standardized and remained largely unchanged until Vatican II.
In these four entries, we find how the Reformation's break with the Roman Catholic church was expressed in the work of various synods, particularly in new documents and confessions. But nowhere was it more clearly visible to the ordinary Christian than in worship itself. Protestants conducted worship in the vernacular and in forms that were distinctly different from those of the Roman church. Perhaps the most powerful expression of this difference was in the emphasis on the Word of God read and expounded.
Between 1600 and 1900, Protestant movements proliferated in a continuous search for biblical Christianity or for renewal and restoration. The result was the establishment of many different worship traditions, as seen in these 11 entries, since these Christian groups tended to express their differences in the language of worship.
Perhaps more attention has been given in past few decades to the deliberate renewal and revision of Christian liturgy than in any previous era in church history. The renewal of worship that began with the neoorthodox movement in Protestantism took root in the Roman Catholic church and has extended to nearly every denomination and community of faith. The following 11 entries discuss the rise of the Pentecostal, charismatic, and praise traditions that have changed the shape of worship throughout the world. Today the two major streams of worship renewal-the liturgical and the charismatic-are converging into new patterns that bear a strong similarity to what some believe early Christian worship was like.