Re: “How Will they Merit Eternal Life”. Your answer raised a few questions in my mind, regarding the tribulation survivors found worthy to enter the kingdom (The Sheep) You said they will have earned eternal life once their natural life ends. Will there be medicine, doctors, hospitals, all of life’s technology that we depend on now, after Jesus returns and sets up his kingdom? If the Tribulation survivors will be re-populating Planet Earth, won’t they be in need of all these things?
The Bible doesn’t provide this kind of detail. However, there are a couple of hints in Scripture that the pharmaceuticals and technology we rely on for health care now may be unnecessary for tribulation survivors, even though they’ll still be in their natural bodies. For example, Ezekiel 47 speaks of a river that will flow from the Temple down to the Dead Sea turning the water there fresh. In Ezek. 47:12 we read that fruit trees will line both banks of the river. Their leaves will not wither and they’ll bear a new crop of fruit every month. The fruit will be for eating and the leaves for healing. This is repeated in Rev. 22:1-3 which also says the curse that came upon Earth when Adam and Eve sinned will be gone.
Also, Isaiah 65:20 says infant mortality will be a thing of the past, and long lifespans will return, perhaps to their pre-flood levels. It says a person who dies at 100 will be thought a mere youth and one who fails to reach 100 will be considered accursed.
I believe this means that sickness and disease will be much less of a factor in Millennial life on Earth than it is today, eliminating the need for the kind of health care we depend upon.