The official and only officially tolerated religion in Saudi Arabia is Islam, and the fundamentalist Wahhabi version of Sunni Islam at that. No other public religious practices are allowed and any such attempts are severely punished by the state.
There are no churches or synagogues in Saudi Arabia. Non-Muslim clergy are not allowed to enter Saudi Arabia. Non-Islamic religious texts and religious items such as rosary beads and crucifixes are similarly not allowed and are confiscated if found.
Saudi Arabia is consistently determined by the U.S. State Department to be a "country of particular concern" for violating international standards of religious freedom. Consistently, if inexplicably, the Secretary of State has granted Saudi Arabia a waiver of sanctions under the International Religious Freedom Act. [The Investigative Project] Read more [via The Iconoclast]