Apparently, the forefather of the Protestant Reformation had a positive opinion of alchemy, and even saw alchemical metaphors in St. John’s Revelation.
According to Lyndy Abraham’s Dictionary of alchemical imagery:
“The science of alchemy I like well, and, indeed, ’tis the philosophy of the ancients. I like it not only for the profits it brings in melting metals, in decocting preparing, extracting, and distilling herbs, roots; I like it also for the sake of the allegory and secret signification, which is exceedingly fine, touching the resurrection of the dead at the last day. For, as in a furnace the fire extracts and separates from a substance the other portions, and carries upward the spirit, the life, the sap, the strength, while the unclean matter, the dregs, remain at the bottom, like a dead and worthless carcass; even so God, at the day of judgment, will separate all things through fire, the righteous from the ungodly.”
Well, he did use a rose and cross as his personal insignia.