If this dude is "just another christian" then you're as crazy as the bible is false.

The establishment clause does not call for a separation of church and state

Takes less than 10 seconds of googling to find out this is false:

By it, the federal government of the United States and, by later extension, the governments of all U.S. states and U.S. territories, are prohibited from establishing or sponsoring religion

The Establishment Clause is a limitation placed upon the United States Congress preventing it from passing legislation establishing an official religion, and by interpretation making it illegal for the government to promote theocracy or promote a specific religion with taxes. The Free Exercise Clause prohibits the government from preventing the free exercise of religion. While the Establishment Clause does prohibit Congress from preferring one religion over another, it does not prohibit the government's involvement with religion to make accommodations for religious observances and practices in order to achieve the purposes of the Free Exercise Clause.

https://en.m.wikipedia.org/wiki/Establishment_Clause

At least do a basic search on a topic before you misinform others.