I don't want to make this into a thread about whether or not you do 'believe' or don't 'believe', but if we had to put ourselves into one column or another, you can safely put me in the 'I BELIEVE' column.
For certain things, there is simply no way imaginable that things are the way they are without some sort of 'intervention' by a 'higher' authority. I have been to Stonehenge and even though they have tried to explain how a bunch of basically 'cave men', built this structure, hauled 3 ton stones from as far as 40 miles away, aligned them in a perfect formation, every one equally distant, equally aligned to the stars and such, and several other things, without any sort of 'higher' beings helping them, well, I just cannot believe it. I also believe that when certain pyramids were built, it was just too coincidental that things were 'arranged' the way they ended up. Sure the Egyptians were smart and could build things, but there are just too many things that they couldn't have known about to do this alone.
Again, just my own opinions, but there is just too much evidence to the contrary that says we have been visited, and may continue to be visited, by beings, not from our universe.