If you use cash you're carrying around advertisements for God.
Michael Newdow is trying to get the government to remove the phrase In God We Trust from US currency. He's basing his argument on the wording of the Religious Freedom and Restoration Act.
He might, instead, want to look more closely at the First Amendment which says, "congress shall make no law respecting an establishment of religion."
The courts have said that this, known as the establishment clause, prohibits congress from establishing one religion over another. The word "establishment" in the clause is not a transitive verb, it is a noun referring to religious organizations. If the clause meant the establishing of religion, it would have used the transitive verb "establishing."
The constitution, the law of the land says that congress shall make no law respecting an establishment of religion. The RFRA is a law respecting an establishment of religion.
Congress has passed tax laws that include in their wording tax exemptions for religious establishments. Those are laws respecting an establishment of religion.
"No law" means just that, none, not any, nowhere, nohow, noway. The RFRA is unconstitutional, just as any other laws passed by congress that refer to religions.
Thanks to the US congress I'm carrying around advertisements for God in my wallet.