Though I might sympathize more with the secular side, there is a certain kind of secular activism which I am squarely against: Trying to purge from public square historic names, seals, flags, whatnot, any vestige of "religion" because such intimates government endorsement of Christianity.
Eugene Volokh noted one such case where the 10th Circuit held that it's constitutional for Las Cruces' City Seal to have three crosses. See the pic.
I think the problem is, America, in principle, indeed has a "core value" that really doesn't favor Christianity over other religions, but rather holds all "religion" have an equal place at the table with secular and pagan philosophies. But this value wasn't meant to work itself out this way, where through court litigation all vestiges of religious imagery that could be potentially interpreted as endorsing one religion over another had to be extirpated from the public square.
If you look at America's and Western Civilization's cultural heritage, it's every bit as pagan (chiefly Greco-Roman, but also Anglo-Saxon paganism) as it is Judeo-Christian. Does having the 5th day of the week named after my favorite Deity Thor the Thunder God signify Thor Worship? Or does having the third month of the year named after Mars bringer of war imply we are a Greek God worshipping nation? In America lots of names of public places reflect our pagan Native American heritage; for instance "Kansas" comes from the Kanza Indians which translates as "People of the Southwind."
If we can get the handful of nuisance secularists (it only takes one person to file a lawsuit) to understand these things are the equivalent of Mars and Thor worship perhaps they'd stop filing these silly lawsuits. But we also need to get the religious side to understand America was NOT founded to be a "Christian Nation" in a public or civil sense. They irk the secular side on with their specious "Christian Nation" arguments.