Isn't every translation a calque, then? I agree that some idioms don't make sense when translated word-for-word and that it's something to be avoided (you're not going to translate "it's raining cats and dogs" as pluit feles et canes), but metaphors are still something a bit different... sometimes when they're very bold they shock me, but this one doesn't (I think the idea behind it might have been understood by a Roman. The past, among other things, contains things you've done, and the future contains things you're going to do - in any language I think). But well... I can understand your hesitation.
I think that the quote is this: ''There is no Saint without a past, no sinner without a future.'' I searched for the supposed original Latin of Saint Augustine, but couId not find it. So I would translate the saying thus: ''Nullus Sanctus sine praeterito, nec peccator sine futuro.'' It is a rather direct translation from English back into understandable church Latin. I hope that this helps!