Speratus, the point on this issue is very simple, heresies are normally regional before they become wide spread (Lovelock worked at NASA and thus known by some here). If you were visiting a Church away from your locale you would not even know 1/2 the problems in the place you were visiting. It would be literally impossible for the elders to examine you on every heresy, et. al. Most Christians cannot even pass a simple test on the Trinity much less an examination on some heretical group in their area. Thus, your premise is very flawed.
Stick to the basics for the examination, if indeed there is any examination at all. I have visited hundreds of Churches and NEVER been examined once before the sacraments, not once. I am not saying this is the correct posture of the Church, but it is a reality in our culture. I wonder how many here have ever been examined on a regular basis when visiting different Churches? This may make a nice poll.
Where in scripture does it say communion practice is determined by the culture? The examination should be kept simple. That's why I suggested the catechism, a tool for teaching children.
Like politics, all heresy is local. It begins with the toleration of a single error by a local congregation. It spreads to other congregations through contacts with visitors. Open communion provides the perfect breeding ground for incubating the infection: The visitor is communed without examination. He then shares his error (e.g., "God reveals Himself in three different ways.") with the weaker members of the church who, as you said, would have trouble passing a simple test on the trinity.
