I went to a shiur by Rav Yosef Kanefsky this afteroon.
In 1859, radical Reform rabbi David Einhorn devised a Reform liturgy for Tisha B'Av that acknowledged past Jewish suffering on this day (the destruction of the two temples, the last one in 70 CE by the Romans) but said that we should look for new temples springing up around the world as we create a universalist messianic age. Reform is the most universalist of the three major Jewish denominations. It started in Germany. It held that Jews should be Germans in the street and Jews at home. That Judaism was a religion, not a nation with a homeland in Zion.
In the Minhag American (1857) prayer book of moderate Reform rabbi Isaac Mayer Wise there is a moderate amount of litury for Tisha B'Av but no call for a fast as traditional Judaism requires. In the revised 1872 version, there is no litury for Tisha B'Av.
Following the Holocaust, Reform became more inclined to Zionism and to observing Tisha B'Av in some form. Some 1959 camp liturgy observed the day but did not mention the Shoah. But 1964 Reform camp liturgy is filled with references to the Holocaust, as is the Reform practice to this day (some Reform temples read Lamentations on erev Tisha B'Av and observe other parts of the traditional liturgy while other Reform organizations have swimming meets on the day).
Reform has varied the most with observance or lack thereof of Tisha B'Av.
Conservative Judaism has always officially stood by Tisha B'Av in theory, but aside from rabbis, few Conservative Jews have observed the day.
Orthodoxy has always held by Tisha B'Av and Jewish Law. Then in 1967, Jerusalem was recaptured. How could Jews then keep praying for the rebuilding of a desolate Jerusalem as the traditional liturgy demands? The Chief Rabbi of Tel Aviv amended one verb and added a word to the prayer to make it fit modern realities. He was widely denounced. Why? Because Orthodox Jews have nightmares about changing their liturgy or other practices.
How many Orthodox Jews does it take to change a lightbulb?
Changes? We never change.
