"Natural Israel" refers to the ethnic tribes of Israel. Ethnic Israel (natural Israel) was the nation of people that God chose to serve as his example to the rest of the world, and the nation he chose to foster the lineage of the Messiah. Hence, "ethnic Israel" (natural Israel) "gave birth" Christ. After failing to destroy Christ, Satan turned his attention to destroy "the woman", which were the apostles and the other founders of the Church, from ethnic Israel.
The "supper of the great God" is meant to be an intentional parallel to the "marriage supper of the Lamb", but they are not the same thing. The "marriage supper of the Lamb" means life for those who are invited to it, but the "supper of the great God" means death for those who are "invited" it.
Thanks for responsing and given clarifications. That helps sharpen my understanding.