Q. How can believing human survivors of the Great Tribulation be allowed into the millennial kingdom as mortals when Paul states clearly in 1 Corinthians 15: 50 that flesh and blood cannot inherit the kingdom of God?
A. In the Millennium there are two places of habitation for believers. Old Testament Jews who are resurrected at the end of the Great Tribulation will live with Jewish believers who survive the Great Tribulation in Israel. Gentile believers who survive will also live on Earth. They and their children will help repopulate the nations. Since this time is primarily for the fulfillment of God’s promises to Israel, Jews call this time the Kingdom Age.
Raptured and resurrected believers from the Church Age will live in the New Jerusalem, which will be located near the Earth, but because of its size (1400 miles square and 1400 miles tall) will not actually be on Earth. This is the exclusive home of the redeemed Church. No human still in the natural state can enter there (Rev. 21:27). This is what Paul referred to as the Kingdom of God in 1 Cor. 15:50.