I ask not only on behalf of these, but also on behalf of those who will believe in me through their word, that they may all be one.
– John 17:20–21a
 The assembly of believers around word and sacrament represents a public event that serves as a witness of faith to the whole world. On behalf of those who will believe — those who will witness these public gatherings around word and sacraments from the outside looking in — the church strives toward unity expressed, at times, in shared worship across communion lines. However, years of entrenched denominational separation more often lead to observations of confusing divisions among the Christian church than its professed unity in Christ.
 Ecumenically cooperative public worship has the power to both proclaim the gospel of Jesus Christ for the sake of the world and to offer a model for accompaniment and cooperation among the people of God. Worship is that sacred arena where the whole, unified body of Christ is gathered together. Individuals, congregations, communities, and communions, all proclaim in silence, praise, petition and gratitude, the fullness of that body. The unique realities for all of our ecumenical partners suggests that, not only are we different parts of the whole body, but indeed we are bound together. Just as the root word for ‘religio’ and ‘ligament,’ is shared, so also worship is where we gather and are drawn together, bound up in the body of Christ.
 Worship planners from different denominational or communion backgrounds should always be encouraged to find ways to work with one another that exude accompaniment, encourage dialogue and flexibility, and result in a deepening awareness of both theological commonalities and differences, precisely as these are reflected in worship practices. Worship planners must always look to the creative impulse far beyond a least-common-denominator approach. Wherever practices flatten theological depth they dishonor the unique ecclesiological sinews within the body of the centrality of worship practice and technique within each communion.
 A primary foundation of ecumenical worship planning is the recognition of the incarnation of God in Jesus Christ through the Holy Spirit in places and experiences outside our own. This recognition necessitates a shared awareness that God is constantly exhilarating many parts of the body. The acceptance of God’s activity in the church encourages descriptive dialogue and open listening precisely because its primary focus is the experience of the incarnate God in, with and through humans endeavoring to bear witness to this experience. If worship is a form of ‘bearing witness to God’s activity in the world,’ then worship planners must always await the in-breaking of the presence of God in something new. In this way, worship planners consider God’s activity, examine the common flow of the gospel through the different parts of the body of Christ, and make decisions in worship that witness to both. In this way, worship remains the crucible of sacred recognition between God’s activity in the body, and the good news for the world.
 Because worship practice reveals and reflects underlying theological commitments that may be distinctly and differently expressed in each Christian communion, worship planners may experience initial conceptual or semantic problems in their activity of planning worship collaboratively. A solid knowledge and awareness of one’s own theological foundations underlying worship practice provides a central place from which to likewise exhibit flexibility for collaborative and creative worship. Practices may be explained in ways that do not rely on denominationally shaped categories, short-hand or catch-phrases. Whenever worship planners meet, a high premium is placed on participants who are skilled in listening and re-imagining how theological concepts and categories fit together. These conversations about liturgical theology will help to find both commonalities and distinctiveness. In turn, the ensuing worship planning will utilize these understandings to plan a worship service that celebrates these examples of unity and diversity.
 A shared worship service that proclaims the unity of the church of Christ in its diversity will be one that contains elements that reflect the gifts and participation of all groups involved. However, care for the integrity of the worship service as a whole is important. Rather than compiling a patchwork of disconnected worship components, worship planners endeavor to maintain the cohesiveness of a complete worship service based on the foundation of shared worship patterns and common understandings of the proclamation and praise of Christian worship.
 In all planning of ecumenical worship services in a North American context, it is important to recognize the practical ecumenical realities of today’s culture that many describe as “post-denominational.” That is, worship planning for ecumenical services may look to the example of the broader culture that tends to flatten denominational differences in favor of functional commonalities in mission, ministry, praise, proclamation and prayer. On the other hand, an ecumenical service of worship also offers reflective opportunities about the experience of worship that may strengthen the understanding of worship practices and the theological foundations they reveal.
Ecumenical Worship Guidelines and ResourcesLiturgy: Practicing Ecumenism Journal of the Liturgical Conference, Volume 10, number 1 (Spring 1992)