Stoic religion

The following passage from Seneca's writings on benefits have me a bit confused:

The Stoics represent the several functions of the Almighty Power under several appelations. When they speak of him as the father and the fountain of all beings, they call him Bacchus: and under the name of Hercules, they denote him to be indefatigable and invincible; and in the contemplation of him in the reason, order, proportion, and window of his proceedings, they call him Mercury; so that which way soever they look and under what name soever they couch their meaning, they never fail of finding him; for he is everywhere.

This sounds a lot like monotheism, and a lot like what I've heard of the Trinity (I'm not Christian, so I don't know these things in detail). I wonder what the story is. Was this a common conception of God?