The Constitution's First Amendment: What Does It Mean?

"Congress shall make no law respecting an establishment of religion----" is usually interpreted to mean that the government shall not establish any religion as the official religion of the state and shall not favor any one religion over all others.

If this is the proper interpretation, then how do we justify putting "In God We Trust" on our coins and currency, or inserting the words "under God" in the pledge of allegiance? Both of these were acts of Congress, and both favor theism over Budhism, Hinduism, paganism, wicca, atheism and plain non-belief.

Is this not a violation of the law established in the Constitution?