He took part to a great number of exhibitions (in Switzerland, France, Italy, Germany, England, Denmark and Japan) and showed a growing interest in various religious and philosophical traditions, like Zen, Buddhism, Sufism, Shaktism, Hölderlin's romantic mystism, the Christian mystics, Neoplatonism, and in the artistic traditions from India and China (Lobue 1985; 1985).
At a time when Neoplatonism in philosophy, as well as philosophy itself in the university, was considered hopelessly outdated, he developed a freshman class called "Dream worlds and real worlds" that brought the message of Plotinus to the most unpromising students; it proved to be immensely popular, disconcerting his academic rivals.
The Neoplatonism of Plotinus and Porphyry has been referred to as in fact being orthodox Platonic philosophy by scholars like John D. Turner.
A permanent alternative spiritual culture of the West is outlined as Lundborg follows the impulse from Eleusis through the Neoplatonism and pantheism of the Middle Ages, the rise of hermeticism and esoteric alchemy during the Renaissance, up to the highly visible psychedelic scenes of the modern world.
His use of the term demiurge (literally, craftsman) for the creator fits Platonic, Neopythagorean, Middle Platonic, and Neoplatonic schools of philosophy, which dominated the learned environment of the eastern Mediterranean, see also Hellenistic Judaism.
The Neoplatonist philosopher Porphyry of Tyre (c. 232–c. 304) authored the 15 volume treatise Against the Christians, proscribed by the Emperors Constantine and Theodosius II, of which only fragments now survive and were collected by Adolf von Harnack.
The Union was ratified at the Council of Florence in 1439 which John attended with 700 followers including Patriarch Joseph II of Constantinople and George Gemistos Plethon, a Neoplatonist philosopher influential among the academics of Italy.