According to the Vatican, alien life is possible and does not contradict a belief in God, and may actually be free from original sin.
If, for example, belief in God was contradicted by the existence of aliens would that make it impossible? I'm seriously wondering this. If the existence of aliens directly contradicted a belief in God would it possible? I think they based the conclusion on an unstated premise "God exists" and anything which contradicts the premise that "God exists" is flawed. The logic goes like this:
Aliens do not preclude existence of God.
Aliens do not create a contradiction in worldview.