Well, there are some differences in Hinduism but a general belief is in reincarnation and that our efforts at spiritual progress gained in our hearts and minds in this life are not all reset to null by decrepitude and death.
It is my understanding that even most Hindu reincarnationists don't have quite that belief.
In any case, neither does Buddhism, at least by my understanding of it. I think you (and others) may be underestimating the true reach of the idea of Interdependent Origination.
Just because the
individual does not return - and as a matter of fact, one of our goals is to
stop the cycle of rebirths - it does not at all follow that our efforts are "reset to null". Quite on the contrary, actually; rebirths are a hurdle to be overcome.
Reincarnations, if I believed them to be real, would probably be very depressing indeed in this regard.
They would reset a lot of good things to null if they existed, at least as proposed by Kardecist Spiritism.
The worldview of the secular Buddhist to me bears too much resemblance to a life spent shoveling water uphill. If I believed there is just this life, I would accept that and make the best of it, but I don't believe I would find much value in serious spiritual striving.
I have no reason to doubt you, but it is just not how it has to be.
Almost all significant religions postulate some kind of continuation in which the virtuous thoughts and actions of our lives effect a continuing future.
So do we. That is something of a cornerstone, even, as is to be expected.
It just turns out that this continuation has no place for the return of individual people. As, frankly, I feel to be only natural.
The details of the full beliefs can be debated.
Indeed.
Well, I understand and even agree with the Buddha's position on not getting overly vexed by metaphysics. But I at least need to know that the fruits of my internal gradual perfecting are not lost at death.
Of course they are not. One does not need to accept reincarnation to know that; one has to accept that life exists.
Many say the Buddha teaches that we are in a karmic cycle and will continue being reborn until we liberate ourselves in Nirvana. And reaching Nirvana for most is a long multi-life process. My point is there is too much for us to understand but we at least need to know some basics.
The basics as I understand it are "we all suffer and inflict complex chains of cause and consequence upon each other" and "therefore, it is for our best nterest to develop skill at doing the best possible thing in each and every situation".
But I suspect you are set on believing on afterlives "proper", and I assume that just will not be enough for you.