[Andrés]

Discussing god existence, the accuracy of the bible, and even all this fight religion vs science, I have my own point of view but I will not join that discussion, just say you have a religious opposition to the existence of aliens and step aside for those who like to see scientific proof before believing something.

Considering the numbers of stars out there, even if a small fraction is similar to our sun and even a small fraction of them is orbited by a planet similar to Earth, there still remain billions of Earth-like worlds only in the Milky Way.
It would be very selfish to believe that Earth is the only inhabited planet in the universe.
Almost sounds like Paulo III telling Copernicus that earth is the center of the universe and it doesn't move. You agree Earth orbits around the sun don't you?

And if they exist and have the same dreams about the stars we have, I think they'll eventually try to reach other worlds, the same way I believe we'll eventually do that ourselves.

I don’t know enough about relativistic physics to seriously discuss if you can move faster than light or not. Most respected scientists claim you can’t, and I’ll take their word.
So unless a warp points, warp-drives, hyperdrives or other bizarre sci-fi twist of physics is possible, travel between even close systems will take several centuries or even millennia.
But that is not proof that interstellar travel is impossible, it just indicates that it takes a long time.

If someone is arriving Earth now, they must have departed from their home planet long before our industrial era, and of course our first radio transmissions haven't reach there yet.

They can have advanced astronomy and be able to determine that Earth is a planet likely to hold life. There must be thousands of planet that fit the basic profile of our planet (assuming it’s similar to theirs and that's how they pinpointed Earth). It must have been a shot in the dark.

For such a long journey, their ship can be a small one carrying a handful of crewers in some sort of animated suspension.
Or it can be a large ship, carrying enough population to live several generations on board during the trip.
They will be cut out of their home, only a few thousand at best alone in a world inhabited by many billions.
Not enough for any war, at least if the objective is conquest even if they're armed with better weapons than ours, so they’ll surely try to be friendly towards the natives.

But of course all of this is a lie, aliens have been among us for a long time.
Not only they can travel several light years in days but they can also shift between dimensions.
Our governants have been replaced by alien replicants, and they are trying to make us fight each other to weaken us and facilitate their invasion plans....