Translation:At what time does he open the church?
It also isn't just used for Christian buildings, but for buildings of other religions as well.
Duo accepts "At what time does he open the mosque?"
DUO accepts "place of worship" but rejects "place of prayer". [I flagged to to bring attention to the latter.]
"Worship" may imply a degree of submission that some belief paths prefer to avoid. Having both " place of worship" and "place of prayer" accepted would increase the range of options available to diverse belief paths. ("Belief path" includes everything from atheism to Confucianism to humanism and other paths that would never describe themselves as "religions", but still gives all respectful representation.)
Thanks for considering this.
For anyone suddenly bewildered by "je" like me: The preposition je can replace any other preposition and remain grammatically correct, albeit more ambiguous. It is usually clear what meaning is intended based on context.
Without context, Donu ĝin je mi could mean any of the following:
Donu ĝin je [al] mi. — “Give it to me.” Donu ĝin je [el] mi. — “Give it from me.” Donu ĝin je [kun] mi. — “Give it with me.”