Note: "One" is used as pronoun which means any person.According to Soren Kierkegaard, the reason to hold religious beliefs is not that they are immediately evident to the believer, but because in the absence of certainty, a person must make what he called a 'leap of faith'.
A. the reason to hold religious beliefs is
not that they are immediately evident to the believer,
but because in the absence of certainty, a person must make what he called a 'leap of faith'
Wrong. Not parallel.
B. one should hold religious beliefs not because their truth is immediately evident, but because, in the absence of certainty, one must make what he called a 'leap of faith'
Correct. not because || but because; "One" is pronoun and means any person ==> "their truth" is correct.
C. the reason for religious belief is
not because their being true is immediately evident,
but that in the absence of certainty, the best thing to do is make a so-called 'leap of faith'
Wrong. Not parallel.
D. one's religious belief is necessary not because the truth is immediately evident, but because in the absence of the definite knowledge of certainty, one must make what he called a 'leap of faith'
Wrong. "One should hold religious belief" differs from "one's religious belief is necessary".
E. religious beliefs should be held not because they are immediately evident to one, but because in the absence of certainty, a 'leap of faith' must be taken by one
Wrong. Passive voice is not preferable. Actually, this question use double passive voices in one sentence, that's weird in GMAT.
Hope it helps.