For example, in the Ethics Spinoza wrote (roughly translated) "eternity cannot be defined in terms of time, or have any relation to time". I puzzled over this idea for many years, extending to decades. More recently I've thought it prescient, in a way anticipating the concept of "space-time". Indeed that may not be coincidental given Einstein's statement that he was strongly influenced by Spinoza.
So it's not a surprise, in fact even reassuring that such insights permeate human thought, as the Zen Mind nicely demonstrates.
Edit: grammar
The real goal of Buddhism is the elimination of suffering in oneself and others and is purposefully silent on the 'big questions.'
[i] http://www.faculty.umb.edu/michael_lafargue/104/204/budd/rdn...
By the way, one religion without leaders and without deities is fundamental Taoism. There's no one who can lead you on the path but you.