For those who enter the Millennial Kingdom still in "human form", when will they receive their new bodies?
The timing of the resurrection of Millennial saints is one of the most challenging questions in scripture, because the Bible does not clearly address this moment. Therefore, we must assume one of two possibilities may be true. Either a Millennial saint receives a new body in a “rapture-like" moment when they turn 100, as suggested by Isaiah 65:20:
Or, a second possibility is that Millennial saints remain alive in their natural bodies through the end of the Millennial Kingdom and are then resurrected at the conclusion of the Millennial Kingdom, as suggested by Revelation 20:4-6
According to v.5, the “rest of the dead” come to life when the 1,000 years are complete, thus putting an end to the “First Resurrection” which is reserved for the saints. Following the end of the Kingdom, the Second Resurrection takes place when all unbelievers are resurrected.
Of these two possibilities, we prefer the second option that when a Kingdom saint dies, the body returns to dust while the spirit is taken to Heaven to await resurrection at the conclusion of the Millennial Kingdom.