Germany’s Catholic bishops will meet in Frankfurt on Thursday to launch their most ambitious effort yet in their role as the church’s liberal vanguard: a two-year series of talks rethinking church teaching and practice on topics including homosexuality, priestly celibacy and the ordination of women.

Conservatives in Germany and abroad are greeting the prospect with alarm, and nowhere more so than in the U.S., whose episcopate has emerged as the western world’s foremost resistance to progressive trends under Pope Francis.

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