Not at all. I presented an ordained Catholic priest who is easily representative of many Christians.
Your instance that only the ideal you present can be held as authoritive is a fallacy; like most groups, Christianity is far too broad and diverse to be characterised by a single example, and there are both good and bad within the group. The Christian who firebombed his Jewish neighbor's house during kristallnacht is just as much part of the fabric of Christendom as is Father Cortese.
We all would like to ignore the bad within the groups we identify with and pretend it doesn't exist or claim that they can't be "real" members of the group, but to do so is detrimental to the group and often dangerous to society at large.
I would accept your reasoning if we Christians didn't believe in the Afterlife (in Hell and Heaven). We do believe in Hell and Heaven, so it doesn't really matter if someone consider themselves Christian in this life, even if they are not.
Because there will be eternal justice in the afterlife, and those who didn't act like Christians will get their eternal "reward".
(even Atheists can act like Christians...so it has nothing to do with religion)