See, you believe the whole Nibiru thing is connected only to Sitchin, it isn't and you'd know that if you bothered to find out.
No, I don't believe it is all connected to Sitchin. I have a very strong suspicion it is so because all the result on Google, for example, lead to that same Sitchin. That, or aliens. Or both.
So, no, I wouldn't call it merely believing.
Like Australis said, post a few links.