Several of Spinoza's fellow travelers were imprisoned and even murdered for their unconventional beliefs. Spinoza dared not venture far from the Hague during his lifetime for good reason. Accusations of atheism were akin to a death sentence. I think Spinoza used the term "God" to defend himself from that charge, albeit unsuccessfully. Deus sive Natura was his way of coding his belief in "God" although not in any conventional sense. Still, it was a bridge far too far for the 17th century.