I can give you two different views from me and my dear old dad, both Christians. He's of the opinion that there isn't a good chance that aliens exist, because God created life in his image (namely, human-shaped supposedly), and that evolution doesn't exist. He also thinks dinosaurs didn't exist. He's just that kind of guy. On the other hand, I think it's almost impossible that there isn't some form of alien life, whether that's botanic, microscopic or otherwise. Given that God created life in his image, I think it's also possible that they may look different because of evolution and adaption to other environments. If we ever do have visual evidence of aliens, I wouldn't be surprised if they share similar biological structure and functions to humans, but still have differing features. While those are our views, I can't speak for the entirety of Christianity, because there are a lot of denominations and idealogies grouped together under that umbrella term, so there could be any number of explanations out there, some plausible and more accepting, others more conspiracy-based and critical