I’ve recently been going through a video study of the Revelation. In the section on Rev 3: 7-13, the teacher says that all gentiles who come to faith during the tribulation will be killed (beheaded). He references Rev 11:7, equating (being) overcome with killed (the 2 witnesses) and then Rev 13:7 (where the beast again overcomes, but gentile believers this time) and then Rev 13:15, where “as many as will not” take the mark are killed. I had always understood that some portion of gentile believers would survive without taking the mark, thereby becoming the sheep in the sheep/goat division. It doesn’t make sense to me that no one but Jews survive into the MK, otherwise how could the “nations” come to Jerusalem to worship since they would all be Israel? So, are all gentile tribulation saints all killed or do some survive?
The Greek word translated nations in the Sheep and Goat judgment (Matt. 25:32) is “ethnos”. It means a multitude of people, and usually refers to gentiles. They are people who will have survived the Great Tribulation and will face the Lord in judgment at the time of the 2nd Coming. Believers will go into the Millennial Kingdom to re-populate the world and unbelievers will be taken off the planet. The notion that no gentiles will survive the Great Tribulation is put to naught by this verse alone.
But as you’ve stated “the nations” will be required to come to Jerusalem to celebrate the Feast of Tabernacles during the Millennium (Zechariah 14:16). The Hebrew word in this verse is “goyim” which when used in the plural always refers to gentiles. The two verses agree that there will be a population of gentiles who survived the Great Tribulation on Earth during the Millennium.