I think there are two separate questions:<p>1) is there other life in the universe?<p>2) is other life visiting Earth?<p>Considering the number of stars in the universe and the potential number of planets around those stars, IMO it is extremely unlikely that our particular star & planet are so special that we are the only life that exists and has ever existed.<p>If you believe that yes, we are that unique, then of course you cannot believe in anyone visiting Earth. If you do believe there is other life in the universe, it's reasonable to believe they travel around, just like we have traveled around.<p>But also, because of the vastness of the universe, if there is other life, IMO it's likely to be so far away that we will never cross paths. It's like 2 grains of sand on a beach getting next to each other.