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
The opposite of "being good at" something would be "being bad at" it.
good and many
There is no such thing as "good evil." Evil is the opposite of good.
They are different because bad is like not good. And not means the opposite. So good and bad is different because these words are the opposite of other. Well, there are many different things different about good and bad. It is like evil and angel. They are bad and good. So, if I wanted to use good in an sentence I would write, "The angel is good." And for bad I would write "The evil is the bad."
Bad guys win, good guys lose.
The opposite of 'malas' (bad) is 'buenas' (good). The words are in the feminine plural.