I am reading the letters of Seneca although it is a reoccurring theme throughout his letters, I have chosen Letter 16: On Philosophy to quote.

Whether the truth, Lucilius, lies in one or in all of these views, we must be philosophers; whether Fate binds us down by an inexorable law, or whether God as arbiter of the universe has arranged everything, or whether Chance drives and tosses human affairs without method, philosophy ought to be our defense.

She will encourage us to obey God cheerfully, but Fortune defiantly; she will teach us to follow God and endure Chance.

He is talking about a singular God. Is it a Hellenic one? If yes which one? Or is it a later Christian alteration to his writings? Who/what is this God?