There was a controversey similar to what is being discussed in this thread, in HOCNA a few years ago. It was instigated by one or two newly-converted individuals in our Church who engaged in an Aristotelian syllogism with our hierarchs, and arrived at this same "light switch" theory. The problem with this theory is that it is identical with the papal heresy of created grace. Ecumenists are definitely outside of the Church, and there are certainly many milestones in recent Church history that we could guess to be the time when they lost their Orthodox Faith, but we would be second-guessing God.
The faith once delivered to the Saints, and transmitted to us from the Holy Fathers, Canons, Holy Tradition, and Church History constitutes the teachings of the Church, NOT WHAT SEEMS LOGICAL TO US.
Our hierarchs in their wisdom issued a statement in March of 2003 in response to this. It can be read at
http://www.homb.org/frameset-postings.htm
Click the link that says "Statement of March 2003." Also keep in mind that the economia applied to Ecumenists is for the purpose of bringing them into the True Church, and not validating them in their heresy.