What? A woman drowned her kids in a bathtub because she heard the voice of god which told her to do it. Religious belief and conviction can indeed and does cause good people to do bad things.

On the other hand, not believing nonsense cannot follow suit.

Can't always blame religion for stupidity. You don't have to be religious to believe in nonsense.

Obviously, there are people who are radical or have psychological conditions.  Authentic Christianity would never allow for this as it goes against the 5th commandment.  Most Christians do an insane amount to help the poor and vulnerable and I would even say moreso than any other group in society.

Which god? Zod?

What century does US live in?

If you watched the Republican debates you'd feel sorry for our country. 

The United States is a Christian nation and it has always been a Christian nation. His words are true. Regardless of the spirit of the constitution, the land was built by Christian settlers. Not muslims, not atheists, etc.

How likely is it that he even believes in a god?

No, it was the first secular nation in the world as far as we know.

On paper but not in practice. The immigrants were Christian practioners of various sects but they were almost all Christian as a matter of fact. The culture was for centuries based on Christian values and beliefs. It was only corroded with the counter-culture in the 60s.