The Christ will come back as he left this Earth...IN A SPACESHIP!

This is the 'way' (the 'manner') the Scriptures speaks about, AND ONLY THIS WAY. Christ IS NOT described as a grown up when he has to come back. You won't find this in the whole Bible. This false idea is just a speculation, an inference of our imagination and narrow-minded beliefs.

You could ask the same way why Jesus-Christ was born as a child and had to die like a simple man (even a simple criminal) while being the Son of God. There is no reason for him to return as a adult when you can clearly read in the Bible that the reincarnation was the common belief in THAT TIME (Jesus' Ministry).

Jesus was asked if John the Baptist was Elijah! Not the spirit of A prophet, but THIS prophet. There are numerous prophets in the Scriptures. There is then no reason to ask him if John The Baptist was Elijah in particular.

So, the reincarnation was clearly admitted in the early hours of the christianity (it was even a reason of a shism). It then means that Christ will be reincarnated for his return, but with a body created by the Heaven, aka the benevolent ETs. But his future ministry as the JUDGE will come when he will be a grown up!