Why do people continue to insist that the United States is a Christian nation?

They've learned an alternate version of history that puts their religion at the center of everything. Some evangelical groups are fond of twisting reality to suit their needs.

There are some people who want to push their religion on other people and they feel the best way to do that is with government. They cannot grasp the idea that freedom of religion can only exist in a country where the government is not involved in religion.

It causes reaction.
Like a little kid doing something 'bad' to get attention is all that is.
They know better, but it is an excuse to go "look at me!", and they never miss one of those.

spewing ignorance isn't illegal.......

It's difficult to understand how unfathomably stupid people are in this country.

Why? --- Because the sphincter of 'christianity' is loosed in the US,
and principles such as common sense and 'free will' no longer prevail or flourish as they once did.

"Good" Men and Women don't need to be from a 'christian' nation, no matter where it is located.
Their very lives and deeds will be seen in the *Eyes of God* ... *that* is what Heaven is for.

It's easy to take over if people believe they founded it.

They have to have something focus on, however absurd. And there are enough stupid people to believe it.

Some christians like to take what is not theirs. The USA was founded as a secular nation, with a constitution that provides freedom of religion for all. A christian nation would not allow that given what the bible says about unbelievers.

More people in the U.S. say they are Christians.

Part of it is cultural and historical. Even though the Founding Fathers of America were clearly influenced by Enlightenment ideas(especially Jefferson) because of the role of the Great Awakenings in American history that created a sense that America is a Christian Nation.

Our founding fathers used Christian principles when creating our country.

Some people have muddied the waters by arguing out of both sides of their mouth.

When railing against Christians trying to "impose Christianity" on the people through the laws Atheists insist the US is a Secular Nation.

But when those same atheist want to point to Manifest Destiny or Slavery as a condemnation of Christianity they assert the US is a Christian Nation.

The fact is the United States was set up as a Democratic Republic.. A Democratic Republic is a government where all are supposed to be governed by the same laws regardless of individual opinions (be they religious, political etc. etc) position or station in life and the laws are made by democratically elected legislators. (We all know that justice can be brought, elected officials create loopholes for themselves to get around the law etc. etc so the US is not a true Republic because in reality we are not all equal under the law, but in principle that is how it should be)

because they are deceived.

a true christian nation doesn't support divorce and remarriage, abortion, same sex marriage, gay parades, and wars etc.

Better study you Federation Papers, the Compacts of each state, the reasons why we have stars that represent states in the flag, how one could not testify in court or hold public office unless they were a professing Christian, not to mention how each president places their hand on the Bible when taking their oath.

well its not an Atheist dictatorship

Well we are a democracy, that's how we got gay marriage legalized. Considering 71% of the population are Christian. It shouldn't be very hard for the majority to vote and make United States a Christian nation.

Why do people continue to insist that the United States is a Christian nation?

It isn't since June 26, 2015.
Why is America so sinful?
Society is getting more rotten by the minute.
It's all according to the plan outlined in the 24 Protocols of the Learned Elders of Sion.
Soon, you'll see people eating dishes made from children, that is, child cannibalism.
It's a big deal that sodomy is legalized because witchcraft and abortion are also legalized at the same time.
God punishes when 3 things are legalized
that is
1)murder (death penalty, abortion, euthanasia, etc.)
2)sodomy
3)witchcraft
Actually, your own government sacrificed people to Satan on 911.
Next sacrifice: Statue of Liberty and some "old" Bridge.
Poor New Yorkers.
Explosion in the sea will flood New York (New Sodom).
Later Los Angeles (New Gomorrah) will be flooded.
America will be flooded up to Alaska probably.
Forgive me.