Answer: The Constitution does not require complete separation of church and state.
Explanation: Daniel Donnelly brought a suit against the mayor of Pawtucket, Rhode Island for including a depiction of the Nativity in the city center. The suit was based on the argument that the Nativity scene violated the Establishment Clause of the First Ammendment. This clause prohibits the establishment of a state religion.
The court decided in 1984 that it did not violate the First Amendment because the clause does not require complete separation of church and state. Also, the display was secular in nature and did not serve any religious purpose. It just provided a context to the holiday.