In a small town, officials want to celebrate a holiday by putting religious decorations on city hall. they claim that they are exercising their first amendment right to worship as they choose. how does this interpretation conflict with the establishment clause?

This interpretation conflicts with the clause because putting decorations of a particular religion in a public setting can be interpreted as imposing that religion on those who do not follow it and this goes against what is spoken in the first constitutional amendment.  In other words, this can prevent people from uniting peacefully, which is explicitly forbidden by the first emanda.

"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."

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