I would call him a god, or at least someone who believes he is a god.
A Muslim or moslem.
Monotheistic, or a monotheist.
A Sun reader.
Lonely. Xenophilic, perhaps.
We can't really answer this question because not everyone believes in aliens (aliens as in space ships)
He/She is called polytheist.
a jackass unless its a proper approch
If you talk to someone that believes they have been abducted, some of them have some really convincing stories.
According to recent studies on the Internet, 20% of the population believe in aliens!
A Blasphemer. You are not Jesus and saying you are is called "Blasphemy"
First learn about aliens and stuff with him then talk about it with him and of course check for proof.
someone who believes they always have an illness and are dying even though theres nothing medically wrong
A pack of aliens.
There has never been any credible, reproducible evidence of the existence ofaliens. Mainstream researchers refer to people who study them as "wing nuts".
because they thought that they were aliens and had the "wrong" believes.