The first career would be enough for most reputations. Swedenborg was assessor of the Swedish Board of Mines, sat in the House of Nobles, and published on algebra, metallurgy, cosmology, and anatomy, his work on the brain and the nervous system was serious enough that later physiologists credited him with anticipating the function of the cerebral cortex and the ductless glands. He designed machines, proposed a nebular hypothesis, and was by any measure a leading figure of the Swedish Enlightenment.
Between 1744 and 1745 he went through a crisis of dreams and visions, recorded in a private journal he never published, which culminated in what he described as a direct commission from Christ. He gave up scientific publication and spent the remaining twenty-seven years writing theology.
The claim on which everything after rests is that his spiritual senses were opened, that he was permitted to move freely in heaven and hell and to converse with angels and spirits daily, and that his description of the spiritual world is a report. He was calm about it, wrote in dry Latin prose, and lived an outwardly ordinary and respectable life throughout, there is no evidence of derangement in his affairs, which is part of what makes him hard to dismiss and impossible to verify. Kant took the trouble to write a whole book about him without settling the question.
The doctrine of correspondences is his most transmitted idea: every natural thing corresponds to a spiritual reality, so the sensible world is a language, and scripture has an internal sense throughout. Through Blake, Coleridge, Emerson, Baudelaire and the Symbolists it became one of the load-bearing ideas of nineteenth-century literature, and through the New Church, spiritualism and the later occult revival it reached the esoteric tradition. He founded no church himself; the New Church was organised by readers after his death.