It depends on the context of the word good. In this instance, the answer seems to be "evil" if you want the opposite of "Mother Theresa was a good person", without the answer "bad".
bad lands
Durable good
Lousy can apply many things that it is helpful to see it in a sentence to determine an opposite. The weather was so lousy that the picnic had to be cancelled. The weather was so wonderful that we all enjoyed the picnic. In my examples, the opposite of lousy is wonderful.
In Newspeak bad is ungood.
The opposite of naughty would be well-behaved, or good. For Santa Claus, the opposite of naughty is "nice."
The opposite of a good idea would be a bad idea. Depending on how bad you could also say terrible idea.
Bad or worst
bad lands
very good
if a is bad, then negative bad or not bad is good.-a means the opposite of a. Since a is negative and the opposite of a negative is positive, -a is positive.
Durable good
To be good at something could be proficient. To be bad at something could, therefore, be deficient. Deficient is an antonym for proficient.
good and many
There is no such thing as "good evil." Evil is the opposite of good.
Bad guys win, good guys lose.
"Worse" is the comparative of "bad". Its opposite is the comparative of "good", in other words "better".
The opposite of 'malas' (bad) is 'buenas' (good). The words are in the feminine plural.