If interested, Soto Zen is non-mystical with no rebirth according to monks like Gudo Nishijima (see his interesting 30 questions below). He has a theory that meditation is a way to balance the autonomic nervous system.http://www.dogensangha.org/questions.html
8. What is Heaven and Hell?
Heaven is a human supposition and Hell is also a human supposition. But when our autonomic nervous system is balanced, it is just Heaven, and when our autonomic nervous system is not balanced, it is just Hell.
16. Where will you be in 100 years from now?
When I die in a few years, not so long from now, everything will become nothing including me, and I will take a rest forever.
20. Does Zazen have a goal?
Zazen has a goal. The goal of Zazen is to practice Zazen itself.