The fig tree was SYMBOLIC of a people who did not produce "good works" or "good fruits" but who were labeled as "God's people". It produced no "fruit" at all. Therefore Jesus cursed it as an example of what would happen to the people it represented who produced no good deeds. What actually DID happen to Jerusalem in history? There's your answer. A fig tree is a valuable tree like the people the story represented and it's fruit is very health-giving.
Spiritual things are spiritually discerned.
This was "Jerusalem" as a whole, not considering the individual person. The city was destroyed as a whole for disobeying God's law.
The popes down through history have not accepted God's law as written, but have changed it to suit their philosophy, and have destroyed their own. If this makes any sense.