I'm not totally following your point, lynx.
Where in scripture do you back up your claim that extra-terrestrials are angels and particularly fallen angels?
Ephesians 6: 12 For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places.
Act 14: 11-12 And when the crowds saw what Paul had done, they lifted up their voices, saying in Lycaonian, “The gods have come down to us in the likeness of men!” Barnabas they called Zeus, and Paul, Hermes, because he was the chief speaker.
Ezkiel 1:1-28
It is a matter of interpratation and how we understand the scriptures. I think we need to know what is angels before we can decide if they are the same as aliens. As Fedusenko point out, angels are not from this earth, so they are aliens. It is just the words we use differently between the authors of the Bible and the people of today.
And I tend to more believe the aliens are fallen angels is because if look at the behavior of the aliens, they act a lot like the fallen angels in the Noah's day. The only other way to be absolutely sure the alien's identity is when they show up, we ask them what do they think about Jesus.
And I have articles to show you, hope you will read it, it is very informative
Aliens in the Bible
http://www.thewatcherfiles.com/aliens_are_fallen_angels.html
UfOs & Bible
http://www.mt.net/~watcher/ufos.html
Why do you think it is necessary for a Christian to have an explanation if the time should come that extra-terrestrials make their existence known to the world?
Because they are coming, and with so many ufos phenomenon and alien abduction, more and more people ask question including believers and non-believers, the existance of alien is challenging fundamental Christian beliefs.