You are struggling, you say, with belief in an afterlife. There are a variety of reassurances one might provide. How I might address a given interlocutor (including you) depends on what sort of background and what set of assumptions he brings to the conversation.
I don’t know you, obviously, but I’ll assume, since you are “an avid reader of the perennialist authors”, that you’ve grasped the distinction between exotericism and esotericism, as well as the parallel distinction between reason and Intellect.
If so, one possible answer to your dilemma is this: what exotericism calls the “afterlife” and envisions as a future state, esotericism views as an “above-life”, a present state of being and consciousness, to which we have access even now, before we die physically, by means of the Intellect (the Nous of the Hesychast Fathers).
So how can you “be at peace with [your] religion’s notion of the afterlife”? By transposing the horizontal “not yet” of the religio formalis into the vertical “now” of the religio cordis. And how are you to supposed to do this? Through a traditional spiritual practice, a practice designed to work on every level of your microcosm: body, emotions, will, and mind.
Some people may be better assisted, at least at first, by “proofs” of a rational kind, or perhaps testimonies from those who have had “near-death experiences”. But the esotericist will always prefer an intellective proof, the sort of proof that requires us to leave Plato’s cave and see the Sun for ourselves.