I doubt that Thomas Jefferson would object to the Nativity scene on the courthouse lawn as suggested by one of your letter guests.
Jefferson not only approved and attended Christian church services held in a government building (U.S. Capitol) during his presidency, he also called for days of prayer, sponsored religious bills, and actively promoted Christian groups and organizations.
The history of the separation between church and state centers on preventing the state from usurping control of the church, either by changing its doctrines or punishing religious expression.
Throughout history, it has not been the church that has persecuted the state, but just the opposite.
In America, the secular and religious have existed peacefully in the public square for hundreds of years. If there is an offense here, it rests with those who promote restriction and/or abolition of religious freedom – a freedom upon which our country was founded.
Thomas Jefferson invited all religious denominations to have a voice in this new world and to do so without fear of government impunity.
I can imagine him standing in the background, with a throng of carolers, singing praise for this unique and rising empire.