to be exact , how many people a christian in america?

79.5% of Americans.

Do the math, I don't know how many citizens we have. =]

And Einstein was NOT Christian. In fact, the VAST MAJORITY of credible scientists are NOT Christian AT ALL. Do not give into their lying garbage whilst they try to convert you.

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║Those who regard a freedom from the false morals and obsolete
║practices regarding sex or religion as debauched are doing naught
║but corrupting their minds with foolishness.
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║My morals come from compassion; my compassion from
║understanding. And I seek to know and understand... everything.
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Unfortunately not as many as there should be. We were a nation founded by Christianity, But as the years have gone on, soooo many people have gotten away from being God centered and have become Self centered.
I am a christian and so is my husband and my 17 yr old son and we are very blessed and thankful of all that our Lord has bestowed on us.
God bless you

Your English isn't bad, I would say roughly over half of the population of the US believes in God. The vast majority of those are Christian.

About 78 percent of the people in the USA consider themselves Christians.

http://religions.pewforum.org/reports

Your english is good enough for me to understand your question.

Based on the Religious Landscape Survey of 2007 (first source link below) and the United States Census from 2000 Census (second source link below), there are approximately 111 million Protestants and 52 million Catholics who are 18 years of age and over. They are both considered to be Christians.

And according to the third source link I posted below, both Stephen Hawking and Albert Einstein are Agnostics, not Christians.
Agnostics believe that the truth to mysteries about death, religion and God are unknown and can not be proven or disproven. So they are different than Christians.

Last numbers I saw said about 87% of Americans (old enough to be polled I assume) claim to be Christians. Liberal church organizations say about 33%, moderates say about 20%, conservatives say about 12%.
So, some may think that it depends on who you listen to.
As for Hawking and Einstein-who really knows. They both made statements that lead us to think they believe in God-but that does not make them a Christian.
Most people in the USA belong to some denomination of Christianity, but they are not Christians themselves. To be a Christian- one must not only believe in God- they must believe Jesus is God.
I seriously doubt if the number of Christians in the USA is 20%.

yes 75% of th population of america say they are christian

Modern, forward thinking people don't have time for silly superstitions.
Many claim to be Xians, but most really aren't
A lot of them claim to be so they can have acceptance by what they perceive as the popular opinion which is to be an Xian.
After all, churches draw a lot of rich business people and most of those (whether they admit it or not) are there for business networking, not because they actually believe the nonsense that goes on there.
I would say in actuality, there are now less than 50% of the total population who can call themselves true Xians and believers.
I can't claim to be one because I can't say it and keep a straight face.
Lying always makes me laugh, so I would be too easy to spot if I tried to join one of their cults.

A footnote, all Xians who give me a thumbs down are just proving my point.
It goes completely against your teachings of judge not and turn the other cheek.
Thanks for your unwitting support and proof of your true disbelief in Xianity.

About 80% of Americans claim to be Chrisitans but that is not an accurate number.

The real number is about 20%

About 76%. Most are located in the Bible belt or Southern states of the U.S. Only about 59% in the Western portion. Statistics are subject to change. These were from a 2008 poll.