Bruno was burnt at the stake for being a heretic.
His heresy went as follows. He postulated
that the stars were much like our sun but just very far away
(first person on record to say so, so he makes into
the list of most influential astronomers of all times).
He continued this line of thought with the idea that
if they were sun's just like ours they probably
had places like the earth associated with them. If this is the case and other people live on these places then how could those peoples soul's be saved if they never had the opportunity to hear the message of Jesus?.
His conclusion was that God would not permit the souls to go to damnation and so multiple copies of Jesus must
have been born and crucified and resurrected, one for
each star in the heavens. At the point the
church stepped in and said
"right, your firewood mate"