To respond appropriately to this question we must first distinguish the behavior and responsibility of an individual member in the local church from that of the church as a corporate entity. In the local churches the decision to participate in joint efforts with other Christian groups is left entirely to the conscience of each individual member. In our standing as the church, however, we feel constrained by the Lord not to promote such efforts. Contrary to what some may claim, this stand does not mean that we consider ourselves more highly than other believers, nor does it mean that we regard ourselves as the only true Christians. Rather, our position is a result of our aspiration to arrive at the genuine oneness to which Christ called us and for which He prayed (John 17:21-23; Eph. 4:11-16).
In response, no doubt, to the biblical call to oneness, Christian groups commonly join together for one of two reasons—to promote a “cause” (emphasizing a particular activity, person, issue, or viewpoint), or to demonstrate their unity (ecumenism). To gather together for a specific cause serves to establish that cause as the center and focus rather than Christ, effectively excluding those believers who may not hold the same view. An ecumenical effort, on the other hand, attempts to unite organizations or denominations in a temporary display of oneness while maintaining the denominational “walls” that divide them. If Christians temporarily work together yet maintain their denominated standing, new believers gained by such efforts are presented with a serious dilemma: With which group do they meet? As new believers join the various denominations, these ecumenical efforts serve to ultimately build up the divided situation they were intended to overcome. Regardless how noble the intentions, both types of efforts compromise and frustrate God’s way of impartial, indivisible, eternal oneness by adulterating with natural human endeavor the purity of Christian oneness revealed in the Bible.
The scriptural way of oneness, the way the local churches seek to follow, is very consistent, definite, practical, and clear (Acts 2:42-47; Rom. 12:4-5; 1 Cor. 1:10-13; 1 Cor. 12:12-27; Col. 3:10-15). The Bible never endorses either a cause or an organization around which believers should unite. In fact, the Bible invariably points us to God Himself as the unique factor of our oneness (John 17:21-23). He alone is the source of our oneness (John 17:11), He is the sole means of our oneness (17:23), and as a result, He is the only One glorified through our oneness (17:21). As Christians seeking diligently to fulfill the Lord’s charge to arrive at and maintain such oneness with our fellow believers, we are bound by our conscience to live so that our testimony would express the oneness revealed in God’s Word for His glory, rather than uplifting any man-made cause or movement.