Stoicism Is a Spiritual Way of Life
The religious impulse of Stoicism is directed toward personal piety rather than public worship. Prayer and worship were certainly included in Stoic practice, and they had a single aim: to bring the thoughts and actions of the individual practitioner into coherence with universal Reason (logos) which pervades the cosmos. As the French philosopher Pierre Hadot argues,
What defined a Stoic above all else was the choice of a life in which every thought, every desire, and every action would be guided by no other law than that of universal Reason.
The goal of bringing our human nature in accord with cosmic Nature, as the path toward virtue and well-being, is so abundantly clear from the Stoic texts that no one conceived of denying it until modern atheists and agnostics began their attempts to conform Stoicism to their worldview. Even though “a number of radical differences” separate traditional monotheistic religions from Stoicism, as A.A. Long argues,
Epictetus’ theological language betokens a personal belief and experience as deep and wholehearted as that of any Jew or Christian or Muslim.
Likewise, as the German ethics professor Christoph Jedan argues,
The religious tenor of Stoic philosophy provides the key for an adequate understanding of Stoic ethics, not only across time but also structurally, by helping us to understand a number of counterintuitive and seemingly incoherent Stoic statements.
Stoicism is not a religion in the traditional sense; however, it is a deeply spiritual way of life designed to transform the practitioner. It does so by changing their conception of good and bad and teaching them to live a life of moral excellence in agreement with cosmic Nature. In other words, a Stoic is one “who wants to be of one mind with God” (Discourses 2.19.26)
The divine and providential cosmos of Stoicism may not seem “credible” to modern academics, and it may be “off-putting” to atheists and agnostics who desire to self-identify as Stoics in our secular age. Nevertheless, cosmic Nature is ubiquitous within the Stoic texts, and it is an integral aspect of Stoic theory and practice. The “God within” was important to Seneca; the God talk of Epictetus was an expression of his piety toward and relationship with the divinity of Nature; and Marcus was serious when he asked himself, in the privacy of his own journal, why he should even “care to go on living in a world devoid of gods or devoid of providence?” Fortunately, Marcus maintained his confidence in the Stoic worldview and followed his expression of potential existential angst with the confident proclamation, “But they do exist, and they do show concern for human affairs, and they have placed it wholly within the power of human beings never to fall into genuine evils” (Meditations 2.11).
Likewise, Seneca succinctly expresses the religious impulse of Stoicism while simultaneously contrasting it with traditional religion,
We do not need to uplift our hands towards heaven, or to beg the keeper of a temple to let us approach his idol’s ear, as if in this way our prayers were more likely to be heard. God is near you, he is with you, he is within you. (Letters 41.1)
Like Marcus, Seneca did not consider life worth living without the existence of God and his ability to contemplate the divine (Preface to Book 1 of Natural Questions). Of course, Epictetus’ personal piety is on display in his suggestion that we should sing perpetual praises to God,
If I were a nightingale, I would perform the work of a nightingale, and if I were a swan, that of a swan. But as it is, I am a rational being, and I must sing the praise of God. This is my work, and I accomplish it, and I will never abandon my post for as long as it is granted to me to remain in it; and I invite all of you to join me in this same song. (Discourses 1.16.20-21)
Epictetus claims to be following the traditional path of the Stoa when he argues the first thing a philosopher should learn is that God exists and providentially administers the cosmos (Discourses 2.14.11). The same kind of reverence is clearly visible in Marcus Aurelius’ profound trust in a providential cosmos for “ethical and emotional support.” Marcus wrote,
Everything suits me that suits your designs, O my universe. Nothing is too early or too late for me that is in your own good time. All is fruit for me that your seasons bring, O nature. All proceeds from you, all subsists in you, and to you all things return. (Meditations 4.23)
The Meditations of Marcus Aurelius have inspired countless people, and that is a good reason why it remains an influential and inspirational part of the Western spiritual and ethical canon into the twenty-first century. American philosopher and religious scholar Jacob Needleman suggests the combination of “metaphysical vision, poetic genius, and the worldly realism of a ruler” within the Meditations of Marcus Aurelius inspire us and give us “honorable and realistic hope in our embattled lives.” As result, he argues,
[The Meditations] deserves its unique place among the writings of the world’s great spiritual philosophers.
Likewise, the Reverend F.W. Farrar concluded,
I know not whether the whole of heathen antiquity, out of its gallery of stately and royal figures, can furnish a nobler, or purer, or more lovable picture than that of this crowned philosopher and laurelled hero, who was yet one of the humblest and one of the most enlightened of all ancient “Seekers after God.”
The deeply spiritual nature of Stoicism is plainly evident to any open-minded reader of the surviving Stoic texts. No, Stoicism is not an institutionalized religion—no one is arguing it is. However, Stoicism is more than stoic ethics, it is more than a path to tranquility, it is more than a life hack, and it is more than a stoical version of Cognitive Behavioral Therapy. Stoicism is a deeply spiritual and philosophical way of life. It was so during the early Stoa, as evidenced by Cleanthes Hymn to Zeus, and it remained so throughout the history of the Stoa, as can be seen in the Letters and Essays of Seneca, the Meditations of Marcus Aurelius, and the Discourses of Epictetus. That spiritual aspect of Stoicism continues to appeal to many moderns because it resonates with our human nature which intuitively knows we are participants in something greater than ourselves.
Within the pages of the Stoic texts, we feel the subtle pull of cosmic Nature—that which we are physically part of, but from which we have become psychically disconnected. Cosmic Nature does not demand obedience to a list of rules; it requests agreement with the events of Nature for our well-being. By living in agreement with cosmic Nature, the excellence of our human nature is realized, and we can experience psychological well-being regardless of external circumstances. Stoicism is not a religion as commonly understood; nevertheless, it remains a viable spiritual path for moderns. The spiritual teachings and practices of Stoicism will not lead you to a temple, church, confessional booth, priest, altar call, tent revival, or set of holy scriptures. Instead, they will lead you to a sacred place inside your psyche where that fragment of the divine within you can reconnect with the divinity that is immanent within Nature to create a rational and meaningful life.
 Pierre Hadot, The Inner Citadel: the Meditations of Marcus Aurelius (Cambridge, MA: Harvard University Press, 1998), 308.
 A. A Long, Epictetus: A Stoic and Socratic Guide to Life (New York: Oxford University Press, 2002), 145–47.
 Christoph Jedan, Stoic Virtues: Chrysippus and the Religious Character of Stoic Ethics (New York: Bloomsbury Academic, 2009), 2.
 Lawrence C. Becker, A New Stoicism (Princeton, N.J.: Princeton University Press, 1998), 6.
 William B. Irvine, A Guide to the Good Life: The Ancient Art of Stoic Joy, 1 edition (Oxford ; New York: Oxford University Press, 2009), 55.
 Christopher Gill, Marcus Aurelius Meditations, Books 1-6 (New York: Oxford University Press, 2013), lxix.
 Jacob Needleman and John Piazza, The Essential Marcus Aurelius (Tarcher/Penguin, 2008), x.
 Ibid., x–xi.
 Rev F. W. Farrar, Seekers After God (New York: Cosimo Classics, 1890), 316–17.