When and why did the Catholic Church stop the Crusades? When and why did the Catholic Church stop the Crusades?

Was there a specific reason why they stopped? Or were they no longer necessary at some point in time?
This answer takes from the article

The Real History of the Crusades, by THOMAS F. MADDEN1 | MARCH 19, 2011 Crisis Magazine.

1. (At the time of the article) Thomas F. Madden is associate professor and chair of the Department of History at Saint Louis University.

Has the record been set straight on the Crusades?


  No. Many historians had been trying to set the record straight on the
  Crusades.


So what is the truth about the Crusades?


  Scholars are still working some of that out.


For what purpose were they?


  [The] Crusades to the East were in every way defensive wars. They were
  a direct response to Muslim aggression — an attempt to turn back or
  defend against Muslim conquests of Christian lands.


Why were they deemed no longer necessary? The answer is in bold.


  The Protestant Reformation, which rejected the papacy and the doctrine
  of indulgence, made Crusades unthinkable for many Europeans, thus
  leaving the fighting to the Catholics. In 1571, a Holy League, which
  was itself a Crusade, defeated the Ottoman fleet at Lepanto. Yet
  military victories like that remained rare. The Muslim threat was
  neutralized economically. As Europe grew in wealth and power, the once
  awesome and sophisticated Turks began to seem backward and pathetic —
  no longer worth a Crusade. The “Sick Man of Europe” limped along
  until the 20th century, when he finally expired, leaving behind the
  present mess of the modern Middle East.




Addendum

As a response to a possible misconception implied in the original phrasing: the Crusades are certainly not a monolithic campaign that ended on a certain date. They were a series of campaigns conducted intermittently over two centuries by different levels of authority (the first was called by a Pope; the seventh was almost exclusive to Louis IX; etc.) When we speak of the Crusades "stopping," we are not talking of an ongoing Crusade being called off, but of a new Crusade not being convoked.



Please see also:


Crash Course on the Crusades, July 24, 2012, by STEVE WEIDENKOPF | Crisis Magazine.