Here is Reverend William White on Duché's spiritual journey:
A remarkably fine voice and graceful action helped to render him very popular as a preacher. His disposition also was amiable. The greatest infirmity attending him was a tendency to change his religious sentiment. A few years after his ministerial settlement he took to the mysticism of Jacob Behmen and William Law. From this he became detached for a time; and his preaching, which was more zealous than either before or after, seemed to me to border on Calvinism; though, probably, he was not aware of, or designed, it. In this interval my personal intercourse with him began; and hav1ng one day asked of him the loan of Law's works, then much talked of, I received a refusal; the reason given being the danger he had formerly been in from reading these books. He relapsed, however, to the theory of the mystics, and continued in it until the troubles which drove him from his native country. In England he became a convert to the opinions of Baron Swedenborg; and in these he continued until his decease.Some "orthodox" consider Swedenborgianism not "Christian" because it denies "the Trinity and the Holy Spirit, the vicarious atonement, and reject[s] Acts and the Pauline epistles ...." Here is another source that views Swedenborgianism as a non-Christian religion. George Washington, on the other hand, seemed to have no problem with the Swedenborgs.