Question

The establishment clause would prevent

a church from being built in a Jewish area
the mayor’s office from displaying a cross
a citizen from placing a religious scene in a business
the president from having a Christmas party at home

Answer 1

The mayor’s office from displaying a cross.

Reason: the Establishment Clause bars government endorsement/establishment of religion, so a government office displaying a religious symbol is problematic. It does not prohibit private citizens or private businesses from religious displays (nor a private Christmas party), and it wouldn’t by itself stop a private church from being built in a Jewish neighborhood.