Christians,where do you draw the line between "real" Christians..?

and "professed" Christians? I am sure some will take this as "bashing".I feel it is a legitimate question. Due to the "was Hitler atheist or Christian" type questions where the answer is usually something like "Just because he SAID he was a Christian doesn't mean he was one. Then we get the statements about "the majority of the US is Christian... Do you understand my confusion and thus my question?Restated,What makes a "true" Christian other than simply stating you are one,and what percentage of America(a guess is fine) do you think are "true" christians,as opposed to the percentage of "professed" Christians? Thank you