a. I am not a member of the Orthodox Presbyterian Church.
b. I never contended that "all other churches" are wrong. I am certain that there will be all manner of Methodists, Baptists, Episcopalians, etc in Paradise.
c. Do you think that "non-Christian religions" are right? Muslims? Buddhists? Wiccans? Pagans?
I don't know. I would be guessing and my view would be prejudiced by the accident of what country I was born in. If I was born in India, I would have about a fifty to one chance against "choosing" Christianity as a religion and more than 100 t0 1 chance against being a Protestant.