From the middle ages to the modern period, European Christians moved from being prepared to fight and die to recover Jerusalem to seemingly accepting that it would be controlled by Muslims. What precipitated this change, when did it occur and how did Western support for Zionism play into this?
EDIT: Perhaps this question is slightly unclear - what I'm asking about is how and why European Christian countries went from being in the position of wanting the Holy Lands but being unable to take them at the end of the Crusades, to being able to take them but unwilling to do so during the late modern period, and what role, if any, political Zionism played in the late 19th/early 20th centuries.
Put simply, the Protestant Reformation hampered European support for the Crusades. The Crusades to the Holy Land: The Essential Reference Guide by Alan V. Murray summarizes its impact on p. 134:
Crusade ideology was surprisingly uniform throughout the centuries spanned by the crusade movement. Its formation, vitality, and survival were ultimately dependent on two principal factors: the idea of Christendom as a geopolitical reference, and the penitential practice of the medieval church. The rise and fall of the idea of Christendom represented by one church led by the pope, which was actively promoted by the Gregorian Reformers of the eleventh century and died down in the aftermath of the Reformation, mirrored the beginning and end of the idea and the practice of crusading. By the same token, the universal acceptance of penitential practice and the belief in the effectiveness of the indulgence enshrined in Roman Catholic doctrine, which were preconditions for creating and sustaining the ideology of the crusade, gained momentum with the crusade movement and were dealt a serious blow during the Reformation. Even though the ideology of the crusade was kept alive after the sixteenth century, most notably in the aspirations of the military orders, its impact dwindled as the arrival of other forms of religious wars led to the formation of new ideologies.
Not a super scholarly source, but it is summed up nicely here:
A new Mamluk sultan, Qalawan, had defeated the Mongols by the end of 1281 and turned his attention back to the Crusaders, capturing Tripoli in 1289. In what was considered the last Crusade, a fleet of warships from Venice and Aragon arrived to defend what remained of the Crusader states in 1290. The following year, Qalawan’s son and successor, al-Ashraf Khalil, marched with a huge army against the coastal port of Acre, the effective capital of the Crusaders in the region since the end of the Third Crusade. After only seven weeks under siege, Acre fell, effectively ending the Crusades in the Holy Land after nearly two centuries. Though the Church organized minor Crusades with limited goals after 1291–mainly military campaigns aimed at pushing Muslims from conquered territory or conquering pagan regions–support for such efforts disappeared in the 16th century, with the rise of the Reformation and the corresponding decline of papal authority.