Saying “under God,” or “praise Jesus,” is perfectly legal and, in fact, protected, by among other things the Free Exercise Clause of the First Amendment. The government forcing teachers and compelling students to recite a given religious assertion is what is improper. While most Christians are ok with the government affirming religious beliefs in America, I suspect they might not so much like it in Iran.
The courts would strike down any legislation declaring America ‘under Jesus’ and Jews would be protected from the government legitimizing anti-Semitism. The real issue in this case is that prejudice against atheists and agnostics has popular support whereas anti-Semitism has got a bit of a bad name. This is why Justice O'Connor referred to objections on Establshment Clause grounds by atheists as a "heckler's veto."
We have the responsibility, Justice O'Connor, to stand up for all minorities, not just those which are considered worthy by a given social context. In fact, history has illustrated that it is the unpopular minorities, which are most vulnerable to mistreatment.