"Now they (in particular Kenneth Cook) are saying that Jesus will deliver the judgment at the Great Tribulation, but that he will do so on the basis of evidence and consideration of actions leading up to the Great Tribulation, just as a judge takes time to consider the evidence before delivering his judgement."
This is exactly what is taught now. That the separation is future but based on what people do now. The future separation is the judge deciding from the evidence of what the people do with the Bible truths that they hear now.