Do you believe in anything you have not experienced personally? Of so, what is it and what led you to believe it?
If you have not experienced it, do you have evidence of it?
If you have no experience of it and no evidence of it, why do you choose to believe in it?
I really don't like the word believe as much as I would prefer provisional trust.
Some things are obvious such as findings and discoveries in the scientific community for which I take people at their word because I'm confident that I can see the evidences first hand with the proper arrangements should I choose to do so.
In regards to less objective views such as rebirth, I resort to the experience by which we are born, for which the state of pre-birth is arguably no different from that of being post deceased , therefore using birth as proof that it is possible to get out of that state for which I resort to an educated guess that rebirth is an actual believable event that is common place whenever conditions and circumstances are favorable for it to happen.
I would much prefer to have my "beliefs" supported objectively in some fashion even though I'm not 100% sure that what I do believe in is actually true.
It's kind of strange to note that I'm more privy in believing in my disbelief rather than disbelieving in what I personally believe.
It generally works well enough so far , but it could also bite me in the *** someday methinks although I doubt I'll still be around to remember any of this in any permanent way past this life.