Growing up a fundamentalist Baptist, I was taught that ecumenism is a bad thing - that it threatened to water down the truth by uniting with false teaching. The roots of this conviction hail back to the beginning of the 20th century, when conservative Christians who were alarmed at rising modernistic trends in the churches (e.g., Darwinism, higher criticism, denial of the miraculous) reaffirmed traditional Protestant theology by staking out certain "fundamental" tenants of the Christian faith. These fundamentals included the inspiration of Scripture, the virgin birth and resurrection of Christ, and atonement for sin through Christ's death on the cross.

As the century progressed, this original fundamentalist movement split into those who remained engaged in the world (present-day "evangelicals") and those who withdrew from the world in an effort to maintain purity (present-day "fundamentalists"). Within the second group, the list of fundamentals expanded beyond the initial understanding of what you believe to include things like what kind of Christian music you listen to, what Bible translation you read, and what clothes you wear. Furthermore, many fundamentalists began advocating what they called "secondary separation" - meaning that churches should not only separate from those they disagreed with, but also from like-minded Christians who had not adequately separated from those they disagreed with. As a result, for these fundamentalist Protestants, the "true Church" ended up consisting of their own local congregations (and perhaps a handful of other people who happened to agree with them on everything).

Key to understanding this fundamentalist separatist impulse is the connection between "the inspiration of Scripture" and "my church's interpretation of Scripture." Thus, other Christians could affirm the entire Nicene and Apostles' Creeds and still be labeled "apostate" because of their method of baptism or preferred Bible translation. In such an atmosphere, ecumenism is next to impossible because there are few to no other Christians left to unite with! In order to achieve true unity, fundamentalists insist that all other Christians must assimilate to the entirety of their congregation's particular interpretation of Scripture.

Although I have focused on fundamentalist Protestants, this model of Christian unity is held by most of the world's Catholic and Orthodox Christians as well. The list of non-negotiable "fundamentals" required for Christian unity is merely substituted for another. Pope Benedict caused a media firestorm in 2007 when he re-released a statement clarifying that Protestants cannot be true churches (in the proper sense) because they lack apostolic succession - ordination at the hands of bishops who are in unbroken unity with the first apostles of Jesus (see: http://www.msnbc.msn.com/id/19692094) Because of this defect, Protestant pastors lack valid ordination and therefore cannot perform valid sacraments. In order to achieve true unity, all other Christians must submit to the apostolic authority of the pope and accept re-ordination at the hands of Catholic bishops (which, at least at this point, would include assimilating to the entirety of Catholic doctrine). Similarly, the Orthodox insist on re-ordination at the hands of their bishops and complete submission to their doctrinal tradition.

Most Catholics and fundamentalist Protestants will concede that people can be true Christians even if they are outside the true Church. In the Vatican II document Unitatis Redintegratio, the Catholic Church clarified that those “who believe in Christ and have been rightly baptized” exist “in a certain communion, albeit imperfect, with the Catholic Church” where their “sacred Christian rites...can truly engender a life of grace and give access to the communion of salvation.” Additionally, these communities have “by no means been deprived of meaning and importance in the mystery of salvation,” for “the Spirit of Christ has not refrained from using them as means of salvation which derive their efficacy from the very fullness of grace and truth entrusted to the Catholic Church.” In other words, there is sufficient overlap with the doctrine of the "one true Church" (be it Catholic or fundamentalist Protestant) to acknowledge that those in other communities can be "Christian" or "saved." However, more is needed - full doctrinal assimilation - in order to achieve Christian unity. In the meantime, there remains one true Church along with many Christians who have not yet fully assimilated to the truth of what it means to be the "Church."

Positively, this approach to Christian unity refuses to be satisfied with a cheap unity that waters down important doctrinal differences. However, if our differences are not essential to what it means to be "Christian," then why should they be essential to what it means to be united as "Church"? After all, to be baptized into Christ is to be a member of Christ's body, the Church. The picture that emerges from the assimilation model is a divided, disfigured Body of Christ - the true Church - with sundry lopped off parts of Christ's Body lying on the ground (Christians, perhaps, but not fully united to the Church). Ironically, such a gory image should provide the needed impetus for Christian unity that other models have failed to achieve.

Catholics, fundamentalists - what are your thoughts? Admittedly, this post is tainted by my own biases as a mainline Protestant. What would you offer as correctives to my analysis? How might you imagine a way forward that is faithful to your understanding of what it means to be Church?