In a recent release, the U.S. military revealed that they have had encounters for years with flying objects that they could not identify. This included video evidence. Some of these UFO’s were flying at hypersonic speeds. So what were they observing? Perhaps it was advanced devices created by China or Russia. That would be scary. Maybe some sort of unidentified illusions. Or perhaps they were encounters with aliens.
Certainly those who promote travel to Mars and other distant planets play the alien life card to garner both public and government support. Most reports suggest erroneously that if you have water then you have life. Life is a very complex thing. Even the simplest forms of life are vastly complex miniature factories. There is no plausible mechanism know that would account the formation of life by unguided processes whether there is water or carbon compounds available or not.
So could God have created other planets with life? Even life reflecting the image of God like us? The idea that we are the sole higher life form created in our universe is more of an inference from the Bible than a statement made by it. The Bible doesn’t speak to the topic. You cannot draw absolute conclusions from silence.
The Bible does talk about other advanced forms of life. Seraphim (burning ones) and cherubim (living ones) are mentioned and described many places in the Bible (Genesis 3, Isaiah 6, Ezekiel 1, Ezekiel 28:14f, and Revelation 4, et al) From the few physical descriptions it is safe to conclude that these are the same thing with different descriptions. This is also what Satan likely is.
Angels are also described many places in the Bible. The word “angel” means “messenger”, so it is more of a job description than a name for a species. Angels and demons would seem to be the same species with different loyalties, but different from Cherubim/Seraphim.
Then there are some more cryptic references. The term “watcher” is used in Daniel, Jeremiah and Job. Who or what does it refer to is unclear. This could be an angel. Job seems to be speaking to God himself. Or it could be something entirely different. Reported encounters with UFO’s are non-interactive. Watching seems to be what is being done.
Another mysterious group is the twenty-four elders around the throne of God (Revelation 4,5,7). No explanation is given as to who or what they are. They are often assumed to be humans, but there is little proof of that.
Finally, there are the “sons of God” mentioned in Genesis 6:2. Often assumed to be angels, this could be a reference to another species or to a group within humanity. Whoever it is they are capable of mating with the “daughters of man”.
God is a very creative being. The vast nature of the universe does not have to exist for any other reason than God wanting to create. That said, God may have wished to create life in some form. The reach of the corruption caused by sin and curse is not described in the Bible. While it affects creation, that could be limited to the Earth. Colossians 1 says this:
For in him (Jesus) all the fullness of God was pleased to dwell, and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross.Colossians 1:19-20 (ESV)
Reconciliation doesn’t seem to apply to Satan nor demons. Who then is reconciled in “heaven”? The word “heaven” can apply to the atmosphere, the universe, or the place where God dwells depending on context.
So if there are aliens, and they are corrupted by sin, then the life, death and resurrection would mean the same for them as us.