I would have to disagree that most people in this country are Christian. Most of them may THINK that they are Christian, but the Bible itself warns of false converts and those who are self-deceived. And THAT is most of your "Christians" in America today.
I used to think, you know, I'm a Christian, I believe in Christ and all that, but I'm just not weird about it. I've since learned that if you're not "weird" about it, you probably aren't saved at all.
Some may throw out the old "No True Scottsman Fallacy" on this, but it simply shows the utter lack of understanding the basics of Christianity in the first place. It's not about trying to look good, or presenting some kind of superiority over other people.
The Bible never hides the shortcomings of the people written about, but records the mistakes these men have made. To me, that really lends to the credibility of Scripture. Why would anyone write down the mistakes and problems of their heroes if it weren't true? David, a man after God's own heart, was an adulterer and murderer, Jacob was a deceiver, and Solomon fell into idolatry. Thomas, one of the twelve disciples doubted, Peter denied Christ when it was convenient, Paul persecuted believers.
None of us are perfect, not one. That is what needs to be understood about Christianity - our NEED of a Savior. And God has provided. When one is truly converted, their lives will show a difference. If guess you can call it a fallacy if you want, and maybe there are some who use it in that way. But a true Christian is a new creation (2 Cor 5:17) and all will be revealed when we stand before Christ to give account for the lives we lived on this earth (Matt 7:21-23), regardless of what you choose to call it.
I'd even have to say that professed Christians in this country don't even have a decent knowledge of the Biblical doctrine.
Here is part of a praise report from my church: This person had recently had a family member die, and had went to the fire station in order to thank the men that helped get her to the hospital. She also shared with them that this family member was saved before she died. Afterward, one of the men asked what she meant by "saved". She got to tell him about the Gospel and has since given him a Bible. Praise God!
You'd be surprised how many people don't have any idea about the very basics of Christianity. And of those who do, they often have a skewed version, never even having read the Bible for themselves.
As one who shares the Gospel with people on a regular basis, I know this fact from personal experience, and it actually surprised me at first, because I also thought that everyone knew what Christianity was all about. I guess it shouldn't have been all that surprising, though, as we see look around at how far our country has turned from basic Biblical teachings to where we are now.
"The chief danger of the 20th century will be religion without the Holy Spirit, Christianity without Christ, forgiveness without repentance, salvation without regeneration, politics without God, and heaven without hell." - William Booth
...And here we are.
They listen to prosperity preachers like Joel Osteen who are nothing more than secular motivational speakers. Some of them watch the antics of Benny Hinn and think that is what Christianity is about. Others think that the Westboro Baptists are Christian. There are heretics in the pulpit, false teachings abound, and Biblical belief is mocked and ridiculed.
There is more need of true Bible-based street preaching than ever before, but it must be in love while never compromising truth. That will offend some, but it should not be our intent.
Soli Deo Gloria