Question:Do aliens or extraterrestrials exist? If they do exist, then how do we respond biblically? I've heard some Christians state that they are fallen angels and that Christ has spoken of things happening from heaven (universe) in Luke 21:11, to provide support for any existence of aliens. But then that entire passage was talking about the destruction of Jerusalem so I'm confused. What do you think?
Peter warned that when someone wants to teach falsehoods, they will twist Scriptures to make them appear to say whatever they want. "Regard the patience of our Lord as salvation; even as our beloved brother Paul also, according to the wisdom given to him, wrote to you; as also in all of his letters, speaking in them of these things. In those, there are some things that are hard understand, which the ignorant and unsettled twist, as they also do to the other Scriptures, to their own destruction" (II Peter 3:15-16). Therefore, the fact that some people try to make a passage discussing the destruction of Jerusalem, which happened in A.D. 70, to say something about extraterrestrials doesn't surprise me.
The Bible speaks of other spiritual beings, angels, who go and come to this world, but it makes no mention of other beings in the physical universe. Some argue that they may be there because the universe is so large, it seems odd that God would create somthing that big just to house man in one little corner. Others, though, point out that God has promised to destroy the heavens and the earth one day with fire. "But the heavens and the earth which are now preserved by the same word, are reserved for fire until the day of judgment and perdition of ungodly men. But, beloved, do not forget this one thing, that with the Lord one day is as a thousand years, and a thousand years as one day. The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance. But the day of the Lord will come as a thief in the night, in which the heavens will pass away with a great noise, and the elements will melt with fervent heat; both the earth and the works that are in it will be burned up. Therefore, since all these things will be dissolved, what manner of persons ought you to be in holy conduct and godliness, looking for and hastening the coming of the day of God, because of which the heavens will be dissolved, being on fire, and the elements will melt with fervent heat?" (II Peter 3:8-12). Why would the worlds of other people be destroyed because of the sins committed on this world?
Since God hasn't told us and we aren't capable of learning it on our own, we will just have to wait until reach heaven to find out.