What is the government not allowed to do with regard to someone's belief in God?

Under current constitutional law, the government can impose restrictions on a religious belief or practice, as long as the law in question applies to everyone and does not target a specific religion or religious practice. The First Amendment  Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.