Frequestly Asked Questions (and answers) about Stoic philosophy
The answer about Stoic theism is usually rather different for modern people who self-identify as Stoics and the classical Greek and Roman view. There are few modern people who share the ancient view. Modern people of a variety of different views about theology have been strongly influenced by Stoicism, but atheists and agnostics are more likely to self-identify as Stoics; comparably influenced theists usually still self-identify with the religion that holds the theological views closest to their own (although there are modern deists and pantheists who self-identify as Stoics).
There is a substantial amount of material in Stoicism which can be adopted to a wide variety of religious beliefs (or non-belief).
As far as the ancient Stoic view goes, this classical account from Diogenes Laertius’s Lives of Eminent Philosophers, book 7, may have the best compact explanation:
[142] …The doctrine that the world is a living being, rational, animate and intelligent, is laid down by Chrysippus in the first book of his treatise On Providence, by Apollodorus in his Physics, and by Posidonius. [143] It is a living thing in the sense of an animate substance endowed with sensation…
[147] The deity, say they, is a living being, immortal, rational, perfect or intelligent in happiness, admitting nothing evil [into him], taking providential care of the world and all that therein is, but he is not of human shape. He is, however, the artificer of the universe and, as it were, the father of all, both in general and in that particular part of him which is all-pervading, and which is called many names according to its various powers. They give the name Dia because all things are due to him; Zeus in so far as he is the cause of life or pervades all life; the name Athena is given, because the ruling part of the divinity extends to the aether; the name Hera marks its extension to the air; he is called Hephaestus since it spreads to the creative fire; Poseidon, since it stretches to the sea; Demeter, since it reaches to the earth. Similarly men have given the deity his other titles, fastening, as best they can, on some one or other of his peculiar attributes.
[148] The substance of God is declared by Zeno to be the whole world and the heaven, as well as by Chrysippus in his first book Of the Gods, and by Posidonius in his first book with the same title. Again, Antipater in the seventh book of his work On the Cosmos says that the substance of God is akin to air, while Boëthus in his work On Nature speaks of the sphere of the fixed stars as the substance of God.
Although the classical Stoics regarded their physics and theology as important parts of Stoicism, at least some of them explicitly recognized that the ethical aspects of the philosophy would still be justified even if their physics and theology were incorrect. More recent people who either consider themselves Stoic, or are deeply influenced by Stoic views, come in many varieties.
Christian, Jewish, and other dualist theologies can be compatible with many elements of Stoic ethics. Indeed, some aspects of modern Christianity were strongly influenced by Stoicism, as the early Roman Christians were often familiar with Stoicism. Greek and particularly Latin were important elements of higher education in Europe for a significant period of time, and Stoic and Stoic-influenced writings (particularly Seneca and Cicero) were popular and influential. The Serenity Prayer has a particularly Stoic character.
Most elements of Stoic ethics are compatible with traditional atheism, and many atheists agree with the deterministic and materialist aspects of historical Stoicism.
Modern variations of pantheism can also be compatible with Stoicism. Naturalistic pantheism, which differs from atheism only in its beliefs about the best attitude to take toward the world, is a natural fit, incorporating the religious flavor of the acceptance of past and present events present in much Stoic writing.