I have been tasting a bit of Tillich's thoughts lately - just a small pdf where he answered questions from an evangelical Christian student about his concept of 'ultimate concern'. Religious philosophy is interesting sometimes and at others times induces sleepiness. But in this case what interested me was Tillich saying that neither Jesus nor the Buddha were religious.
What I take from this is related to two artificial concepts I use when I teach history of religion at the university level. I borrowed two terms from Latin and twisted them somewhat: religio and spiritus. By religio I mean the institutional face of religion - structured, organized Christian denominations, Islamic mosques and nations, synagogues, temples, rules, regulations, theologies, philosophies. By spiritus I mean the inner spirituality of the individual believer or believers in groups. Despite the best hopes, efforts and often threats (both theological threats and physical!) of religious professionals, ordinary believers often only share partially in the official dogma and doctrine of a religion. In situations where religion and the state work in tandem, this spiritus may be hidden and outwardly all believers conform. In the democratic West, where believers used to conform outwardly due to social pressures, now pretty much anything goes. This does not mean, however, that the two never touch. Actually they are tangled up together, but just in an asymmetrical fashion.
Being a simple historian in the British empiricist tradition, I was left confused as to what Tillich meant by saying neither Jesus nor the Buddha were religious, so I squeezed this thought into my own wineskin (see Matthew 9:17 "Neither is new wine put into old wineskins. If it is, the skins burst and the wine is spilled and the skins are destroyed. But new wine is put into fresh wineskins, and so both are preserved.”). Both Jesus and the Buddha broke the rules of their religions and the societies within which they were integral. Jesus the Jew and Siddhartha the Hindu poured their truth into new wineskins. That is, they were filled with spiritus but not so much followers of religio.