Republican Congressional Delegation now 100% Christian

[DC Al Fine]

But I'd still count the Mormons as non-Christians anyway.

Regardless of what you think of them (not that I disagree),  Mainline v Catholic v Evangelical is still the most relevant divider since that covers a large majority of Congress.

[DC Al Fine]

If Mormonism is Christianity, North Korea is a democracy.

Its Christology is basically Arian. How is that less any Christian than, say, Jehovah's Witnesses or Oneness Pentecostalism?

Jehovah's Witnesses are not Christian, either.  I've never heard of Oneness Pentecostalism, but I would assume they are not, either.

How are Mormons and Jehovah's Witnesses not Christian?  Is it just because they created their doctrines and made up their beliefs more recently than other Christian denominations?

I can't speak for the JW's, but the Mormon's theology, especially their Christology is different enough from mainstream Christianity to consider them a fourth Abrahamic religion.