Certainly a valiant effort, and in some regards persuasive. BUT:

The Hamtranck ordinance violates the free speech part of the First Amendment.

"Under God" is in a pledge that atheist children are required to recite, which makes theism an established religion. Recall that the words were inserted in the pledge to counteract the "Godless" Commies, i.e., to establish theism as an essential element of Americanism. It was wrong then, and it is wrong now. (Side note: I attended the same high school as the late U.S. Poet Laureate Louise Gluck. Louise’s claim to fame back then was an editorial in the high school newspaper protesting the insertion of "under God" into the pledge we all recited every morning. Her efforts were not well-received by many in the faculty; I thought she had a point.)

"In God We Trust" is less offensive, because we don't have to say it to use the money.

Lots of religions don't regard the Decalogue as part of their religious scheme. REQUIRING that the Ten Commandments be posted in schools clearly establishes the Judeo-Christian beliefs as a state religion.

Atheism may be a religion, but it has no religious symbols. Atheists don't demand "There is no God" be posted in every classroom. That would be much closer to the point you are arguing. Indeed, if the legislature commanded such a posting, I think you could make your case against it.