Can we come up with a list for this one?
1) The earth is flat. Galileo got in big trouble for doubting this "Church teaching."
2) Heretics should be burned at the stake. This Church teaching was true at one point...must still be true. Ouch! Quit, you're hurting me! Hey, that's hot!!! Stop that!!
More???
And what's wrong with burning heretics? Its not like it is against the will of the Holy Spirit.
If any one abide not in me, he shall be cast forth as a branch and shall wither: and they shall gather him up and cast him into the fire: and he burneth. (John 15.6)
Wizards thou shalt not suffer to live. (Exodus 22.18)
A man, or woman, in whom there is a pythonical or divining spirit, dying let them die. They shall stone them. Their blood be upon them. (Leviticus 20.27)