There's no reason why God should be the first cause.
Summary
Quotes
“Incidentally, even if we were to agree with Leibniz and the principle of reason, this would only prove the existence of a necessary being. But what proof do we have that this being is God, by which I mean a Spirit, a Subject, a Person (or three)? It could just as easily be Anaximander's "apeiron" (the infinite, the indeterminate), Heraclitus' ever-changing fire (becoming), Parmenides' impersonal Being, Lao-tseu's equally impersonal Tao.... It could be Spinoza's Substance, which is absolutely necessary, the cause of itself and of everything, eternal and infinite, but immanent (its effects are in itself) and devoid, as I said in connection with ontological proof, of all anthropomorphic features: it is without consciousness, without will, without love. Spinoza calls it "God", of course, but it's not a good God: it's only Nature (this is what we call Spinozist pantheism: "Deus sive Natura", God that is Nature), which is not a subject and pursues no goal. What's the point of praying to it, since it doesn't listen to us? How can we obey her, when she asks nothing of us? Why trust her, when she doesn't care about us? And what's left of faith? Leibniz made no mistake. This kind of pantheism is closer to atheism than to religion.”