Why are my clothes red?

They are fascists. Fascist christians vs christians.

If you read the fallacy you'd realize that you fell into the false fallacy fallacy.

To quote your linked article:

No true Scotsman or appeal to purity is an informal fallacy in which one attempts to protect their generalized statement from a falsifying counterexample by excluding the counterexample improperly.[1][2][3] Rather than abandoning the falsified universal generalization or providing evidence that would disqualify the falsifying counterexample, a slightly modified generalization is constructed ad-hoc to definitionally exclude the undesirable specific case and similar counterexamples by appeal to rhetoric.

There is plenty of countries with a christian background and still majority christian population, that wouldn't even think to discuss such absurd policies. American nutjobs cannot be considered to be representative of christianity as a whole. Much of their nutjobbery is specific to them.

If we were to play it your way, the Crusaders weren’t Christians, the Spanish Inquisition weren’t Christians, the Conquistadors weren’t Christians, etc

All of the above are Catholic, and the vast majority of Christians I know would agree that they aren't Christian.