The Pearly gates, in Christianity, is an informal name for the gateway to Heaven, inspired by the description of the New Jerusalem in Revelation 21:21— And the twelve gates were twelve pearls; every several gate was of one pearl: ...
The image of the gates in popular culture is a set of large, white, wrought-iron gates in the clouds, guarded by Saint Peter. Those not fit to enter heaven are denied entrance at the gates, and thus descend into hell.