If a person thinks that aliens exist, that means they don't believe that GOD sent his only Begotten son to save the "WORLD". Not worlds. Did GOD send His son to other planets with other beings to save them as well? Ridiculous and a grave sin. They are either demons or they are creatures that man put together like Frankenstein!
A Bishop told me that he will commit murder if his conscience told him to.
In other words, he was saying, not to listen to our conscious. It can lead us to do many evil and stupid and dangerous things.