Which idea shows the government refusing to promote or forbid a religion

Separation of church and state -

The First Amendment states that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof."

That ideal is that of Religious Liberty. It is stated in the First Ammendment of the Constitution of the United States of America.

Explanation:

Liberty is the same as freedom.

In the First Ammendment, it is guaranteed to all US citizens that they are both free to believe and express their belief in any religion. It also assures that the Government cannot favour one religion over another, or non-religion over religion abiding citizens and practices.