Answer:
During his time he was considered one. The church strongly rejected many of his ideas, especially the fact that he had proof supporting the heliocentric theory. To put it simply the church has been really dumb for most of history and Galileo was way smarter.
Explanation:
Heresy is defined as: any belief or theory that is strongly at variance with established beliefs or customs, in particular the accepted beliefs of a church or religious organization.
