What did Spinoza believe in?
Spinoza believed that God is not a transcendent being
independent of the universe but an infinite substance that is the
rational structure of the universe. The infinite substance is
infinite because it has infinite attributes, but two of which are
known to us, which are extension and thought. While the Substance
has attributes, each of which is the reflection of its nature, it
also has modes/modifications. Modes are individual physical
entities that partake in the substance and are conceived through
the substance. Without the Substance there can be no modes. In a
sense each mode is a particular manifestation of the Substance. All
modes, however, are finite in that they are always contingent on
one another, but the substance is self-evident and self-explanatory
because it pertains both essence and existence.
This whole metaphysical layout is a significant background that
defines and explains human nature. In the case of the mind-body,
Spinoza believes that the attributes of God (thought and extension)
are merely aspects of God rather than distinct parts of God. Based
on this understanding both the body and the mind are the same (By
the way, just in case you don't know, extension is another word for
material bodies). For Spinoza human nature can be understood
rationally, but ironically Spinoza believes that desire or appetite
constitutes human nature. Human beings have Conatus, which is
basically a driver for both self-preservation (persistent to exist)
and a strive for greater perfection (more joy). Unlike the stoics,
Spinoza did not believe in the elimination of passion but the
moderation and control of passion guided by understanding. It is by
understanding our own emotions that makes us into active agents
that is effected by our internal understanding rather than the
external events that incites our emotions (making us into passive
agents, rather than active).
In a sense Spinoza is a hard determinist because he believes
that human actions have a cause, which is naturally desire. But
this did not mean that we have no control over out action because
Spinoza also believes that by understanding our own desires we know
how to control it (think of it as reason causing emotions or
passions to become passive to its cause). So in some sense Spinoza
is a compatibalist, although this can be disputed.
For Spinoza the ultimate purpose in life is to have an
intellectual love for God or to understand how all things
(including yourself) are essentially united to God. This leads to a
form of salvation that frees from the bondage of passion. For
Spinoza this bondage of the passions is not just mere passions but
from the turmoil of human existence or the tendency to have a
contingent understanding of human happiness (wealth, power,
prestige, romantic love, material goods, etc.).
In a sense Spinoza is a pantheist (or Pandeist) or Panentheist.
However some called him an Atheist (some atheists also see him as
an naturalist atheist). It is difficult to decide which category
Spinoza belongs to, but it is obvious that Spinoza believed in an
infinite substance that is self-existing.