Spinoza, Atheism and Reason

Hello Rabbi.
It is common to see Spinoza as the "atheist," who presented a completely methodical metaphysical theory that leaves God out of the picture – if God is nature and nature is God, then the term God is emptied of all accepted meaning. But in my understanding, one of the things Spinoza did well was actually solve his "reduction problem," in that while the reduction deals with the question of how there is a reality external to God while He is the "absolute one," and solves it by God "reducing Himself" (whatever the intention may be), Spinoza simply claims that the problem begins with us – God and nature are identical and thus nature is the "absolute one" and anything that seems to us to be a lack of uniformity stems from our lack of understanding, and from Spinoza's perspective, his goal is to transcend and enlighten the unity of everything until he understands it and no longer sees reality as a multiplicity…
And the question that arises is – isn't Spinoza's solution more logical and coherent than the reduction?
The second thing that Spinoza does is define nature as its own cause (and hence he also goes on to call it God), but in fact it can be said that "its own cause" is the same as "without cause", because a cause by definition is a prior cause of something, whether in time or in cause, and logically it is also difficult to say that the thing is the prior cause of itself, because it itself already existed at the time it caused it/"at the causal level" that caused it, etc.
And hence Spinoza opens the door to claiming that nature does not need a cause at all, and the question arises – does nature indeed not need a cause? Even if we talk about the Big Bang and deny the antecedents, it is difficult to talk about a cause for the bang itself, since everything began there – even the concept of causality, whether in time or in cause, while for all those who deal with philosophy and religion and attempt to bridge it, it seems necessary to talk about a cause distinct from the universe itself…
I would appreciate a detailed answer, thank you very much Rabbi