The article gives the example of the Crusades, which killed millions number of people on both sides generation after generation, and kept the development of the whole world back for centuries.
In the present day, Americans Christians overwhelmingly revere the monster Trump, a man who flouts most of the Ten Commandments, a pathological liar and malignant narcissist, a man who never goes to church, has never quoted a Bible verse and indeed was unable to name any book in the Bible - and and the most common reason they give for supporting this foul idiot is God.
Nothing could tarnish Christianity more than its deep relationship with the cruel, delusional and incompetent Republicans.