Evangelicals often talk of the slippery slope. Have you ever heard these phrases?
“If we compromise on male leadership in the church, it will lead down a path of …”
“If we compromise on creationism, it will lead …”
“If we compromise on homosexual pastors, it will lead….”
“If we compromise on the literal interpretation of God’s word, it will lead ….”
I had to get pass the endless worries about the slippery slope. Instead of a slippery slope, I now believe the path to heresy is a steep cliff, and only one thing causes us to jump off that cliff. For a former Baptist, the answer to this question in my life was quite surprising, the Nicene Creed. I came to the conclusion that I could put up with almost any belief, as long as it was consistent with the Nicene Creed.
This is much more constricting that many would believe. It definitely gets rid of Mormons and Jehovah Witnesses. If you believe (as I do) that the Nicene Creed presupposes the Trinity, then it also gets rid of many Pentecostals and most oneness evangelical groups. If your church treats Christ and God as the same entity, they might be close to being inconsistent with the Nicene Creed. If your church treats Christ and the Holy Spirit as one entity which empowers you to live the abundant life, they might be close to being inconsistent with the Nicene Creed.
I do not know exactly where to draw a line, especially in regards to the Trinity. But I am convinced that the early Christians did well to document and pass down the heritage of the Nicene Creed.