Spoken like a true 12 Stepper.
One need not "must accept" anything in Buddhism. There are many atheist Buddhists who don't feel a need to believe in reincarnation or in Karma as an external force rather than an internal result of one's thinking and actions. Nirvana is a mental state of "cooling off" not a physical place.
"Do not believe what your teacher tells you merely out of respect for your teacher." - Buddha
"Doubt everything. Find your own light." - Buddha
"To insist on a spiritual practice that served you in the past is to carry the raft on your back after you have crossed the river." - Buddha
"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense." - Buddha
I have a Thai Buddhist friend and when she talks it sometimes sounds like there isn't much of a difference between god and Buddha. I am fairly sure that in original Buddhism the goal is a 'state of mind' (Not a destination) called Nirvana. However, like most everything else, christianity has bastardized that message. I presume she doesn't even know that she's doing it, though it is entirely possible that she may be just appeasing her xtian peers. Seems dishonest but unless you have experienced Alaska for some extended time you can't really understand how theocratic the prevailing mindset here is.
Sometimes it seems that even Utah may be more secular than AK.
I wrote something here a while back that touches on some of these issues.
"Theravada Buddhism, atheism, and clearing up some misconceptions"
There's a big difference between 'real' Buddhism and what people believe it to be...