The National Day of Reason is a secular celebration for humanists, atheists, secularists, and freethinkers. The day is celebrated annually on the first Thursday in May, in response to the statutory observance of a National Day of Prayer in the United States, which many atheist and secular groups deem unconstitutional. The purpose of the National Day of Reason is to "celebrate reason—a concept all Americans can support—and to raise public awareness about the persistent threat to religious liberty posed by government intrusion into the private sphere of worship." The National Day of Reason is also meant to help build community among the non-religious in the United States.