OMG - this made me literrally LOL. :D

Or at the very least, not an Episcopalian.

Reminds me of a bit of history from the 1906 SF earthquake. One of the few downtown buildings that managed not to burn was a liquor warehouse. Its survival inspired some wag to pen this little ditty:

"If, as they say, God spanked this town
For being much too frisky,
Why did He burn His churches down
And save Hotaling's Whiskey?"

Congress has designated the Washington National Cathedral as the "National House of Prayer" which means that legally the Cathedral is nondenominational so perhaps God is telling us he's not an atheist.

Sorry, no. It's an Episcopal church.

From Wikipedia:

Wait, maybe it is just that she views 14-wheeled vehicles as an abomination.

That is correct, but legally it's still a nondenominational "National House of prayer" I believe the congressional designation was granted so they could hold state events there without it being an Episcopal service.

Source?

For starters the same Wiki article you mentioned.

I'm curious to. I'm not finding any record of congress making any such designation (though record of politicians informally referring to it that way). Also not finding any reference at the cathedrals web site or the Protestant Episcopal Cathedral Foundation's (the organization originally chartered by Congress in 1893 to build one) to technical non-denominationalism. In fact it all seems to be very overt in its Episcopalianism and Christianiaty.

ETA: Here's the full text of the original congressional charter.

Declaring it a "National House of Prayer" is not the same as making it "legally non-denominational".