"I believe" means you've started with the conclusion.

"I theorize" means you have an idea about how the world works, about which you genuinely invite criticism and welcome its demise if it's wrong.

I've you've started with the conclusion, your plan is to tie yourself to the mast until you are vindicated as being "right all along".

Maybe "belief" has served you well in the past. Maybe you can brush over some oopsies and move on because most things fundamentally do not matter.

But if you are tied to the mast...

When you were naive and trusting and generally wanting to make a good impression vis-a-vi the Captain and your introduction to this new way of thinking about things was

Now listen good. You're going to get some blowback throughout life for believing this, but

...theory laid out...

And that's something you and I believe. You understand little fella?

If that was your introduction to this particular viewpoint, which was entirely new to you at the time, you'd be pretty clear about where you and Captain stand on this! Together!

And that force becomes the driver for your ability to cling to the arbitrary, come what may.

Really, you are a domino in a long line of utterly pointless cultural dominos. Whatever it is it probably feels like a Great Important Movement that will surely go down in the history books (where you are finally vindicated; post-mortem.)

Having that waived in your face hurts you way down there where the little scared child lives.