Steven: Help me understand!

You say Spinoza is among the most logical, yet I cannot parse this most basic argument as anything but nonesense:

In a very basic form, the Argument works like this: a perfect being must exist, if it doesn’t then it is not perfect. God is perfect and therefore must exist.

This is not a syllogism. If I substitute other terms in here, the result is garbage:

Unicorns must exist. If not, then no one-horned horses exist. Unicorns are one horned-horses, therefore unicorns exist.

Einstein thought this guys was a smart guy, and Einstein is alot smarter than me, so I think something has been lost here in summarizing his philosophy!

Any help?

— Dan