The Inquisition deemed Postel insane rather than heretical

Evidence

However, the Inquisition, in an unusually benign frame of mind, decreed that he was not a heretic, merely insane. An official of the Holy Office, who had examined Postel’s writings for heresy in 1555, reported that, though his ideas were definitely heretical, ‘no one, fortunately, could possibly understand them except the author’. — Robert Irwin, For Lust of Knowing, 126