Mr. Serwer is wrong. The deepness of the division unleashes nastiness on both sides. Being strongly associated with one side only, the author sees as justifiable dismissive attitude given to his opponents. He prefers to point to the nasty margin on the other side, and to ignore the intellectual part of it.
The division we face is about if the fundamental concepts of our political system, as outlined in the nation’s origins reaching back to 1776 are still valid today. If we accept these concepts, we should stand for the free market economy and a small government. We should stand for America strong not by what the government does for its people but by what people do without the government involvement.
The side that Mr. Serwer represents opts for the government taking care of everything. It is called socialism, and it is a plain contradiction to the concepts that America was founded upon.
The real division in the United States of America today is between people supporting capitalism and people supporting socialism. Suggested reading: https://medium.com/@hak1010/capitalism-versus-socialism-9ece51b5ff29.