And if you think that only the best Christians get to have a say in how Christianity is defined or get to be pointed to as examples of the faith, you're committing the exact same logical fallacy.
I don't agree. Why wouldn't I want to see Christianity live up to it's best ideals, rather than the worst? If I say that Trump has an un-American attitude, I am not questioning his citizenship, nor denying that he and his millions of crazy followers exist. I'm just pointing out the contradiction between his rhetoric and its effects, and the best that America has been at other times in history.
The "correct" form of Christianity, to me, is not defined by numbers, nor by credentials of any sort, rather by internal coherence and the most positive manifestation of its ideals. I feel the same way about other faiths - they should not be judged by the products of political and social malfunction, but by the best things they have offered the world. Complaining about the worst manifestations of a neighboring faith may be satisfying in a petty way, but it only leads to war and mayhem.
And it's fine for you to take that stance and say that this is what Christianity
should be. It's also fine for a Muslim to stand up and say that his faith
should be a religion of peace.
What's not fine is when you tell other Christians who disagree with you that they're wrong about being part of Christianity. When the Westboro Baptists protest funerals and say that the soldiers being buried died because God is telling America that he hates fags, they are basing their positions on Biblical references, so someone saying that they are not a valid representation of Christianity is incorrect. When parents sit back and let their child die from a treatable disease because their preacher was telling them about the healing power of prayer, someone saying that this is not a valid representation of Christianity is incorrect.
Every one of those people
agrees with you that they want to see Christianity live up its best ideals and could all very well see your more liberal definition of the faith as a watering down of the Word of God, which is the worst thing that a "so called" Christian could do to the faith.
I agree with you that it's not about the numbers. If you're the one person on the planet who interprets Christianity in a certain way, your version of Christianity is just as valid as an opposing view agreed to by hundreds of millions. If those hundreds of millions tell that one guy he's wrong, however, they're all just as incorrect as he would be telling them the same thing.