Greendawn
From what I have read of the early history of the Christian church there were already seeds of controversy from the early beginning. (Gnostics, Judaizers, etc.) But the main body of believers held to the basic teachings of Christ and kept a reasonable acceptance of their Christian brothers who may have disagreed with some doctrines. The "good news" of their time was that Christ had come, given his life in sacrifice and was now exalted to heaven to be with His Father. It's only when the expectations of his early return came to disappointment and when efforts were made by various leaders to control the believers that the early church began to fragment. I think this disintegration started in the 2nd century after Christ's death. By Constantine's time, the "bishops" were well established over their control over the churches. But "orthodoxy" still was still "in flux" as evidenced by the trinity controversy.
Only God will be the judge of who the true Christians are. From what I have read in the Bible, one is judged by one's own "deeds" not doctrine. (Remember the Good Samaritan?) And the Watchtower will come under the heavier judgment of God if it has spurned some of Christ's brothers.