Gov. Lincoln Chafee of Rhode Island has declared May 1 as a "Day of Reason" in his state.
The secular celebration is being held on the same day as the National Day of Prayer.
Atheists and secularists oppose a national day of prayer, saying it's part of a "persistent threat" to the separation of church and state. They think a "Day of Reason" will help them fight back.
The Humanists of Rhode Island and the Secular Coalition for Rhode Island requested the event.
Chafee's proclamation says reason has "proven to offer hope for human survival upon Earth by cultivating intelligent, moral, and ethical interaction among people."
Meanwhile, millions of Christians are expected to participate in the National Day of Prayer.
This year's theme, "One Voice, United in Prayer," emphasizes the need for individuals, both personally and corporately, to place their faith in the "unfailing character of their Creator, who is sovereign over all governments, authorities, and men."
The theme Scripture for this year's event is Romans 15:6: "So that with one mind and one voice you may glorify the God and Father of our Lord Jesus Christ."