Camping's organization isn't mainstream for sure, but his teachings still fit with a lot of people. Not the specific day, but "soon".
EDIT: These are for Christ returning by the year 2050.
EDIT: Just to clarify, I don't think Camping represents even the most evangelical groups, I'm not trying to say that Camping is representative of evangelicals, just that the difference with respect to "the end" is only in degree.
And it's not atheists that claim religion is dying, it's the statistics that show religion is on the decline. An overall trend does not preclude variations within the whole.