Article doesn't call David 'perfect', just great. He is called 'a man after God's heart'. Since his works obviously weren't perfect, how could this be?
As for Luther, no one calls him perfect. You called him an anti-semite which he was, that qualified him as 'evil person'. Yet the same sin acted upon as the Popes did doesn't qualify as evil with you, just 'imperfect'.
Our oxen NEVER get gored!!!