Catholic Christians simply
accept Christ's explanation of those
still alive at the end of the
world.
Matthew 24:36-42
(In reply, Jesus said to them:) "But of that day and
hour
no one knows, neither the angels of heaven, nor the
Son, but the Father alone. For as it was in the days
of Noah, so it will be at the coming of the Son of Man.
In (those) days before the flood, they were eating and
drinking, marrying and giving in marriage, up to the day
that Noah entered the ark. They did not know until the
flood came and carried them all away. So will it be
(also) at the coming of the Son of Man. Two men will
be out in the field; one will be taken, and one will be
left. Two women will be grinding at the mill; one will
be taken, and
one will be left. Therefore, stay awake!
For you do not know on which day your Lord will
come."