Cayetano Ripoll was the last person executed in Spain for the heresy of believing that observation and logical reasoning were enough to reach divine understanding. You know, that thing St. Paul said in the bible.

For since the creation of the world God’s invisible attributes—his eternal power and divine nature—have been understood and observed by what he made, so that people are without excuse.

Romans 1:20 (NIV)

He was hanged by the civil authority, which made the church folks all kinds of mad. By some accounts, they put Cayetano Ripoll’s body in a barrel and burned it.