So never speak against brutal aggressors who commit war crimes? That seems to be antithetical to Christian values.

Comdemning evil is an act with many purposes. Making the evil-doer change his mind is just one of possible benefit. Even if that is unlikely the other ones remain.

* People naturally imitate what they see others do. A condemnation can prevent others from imitating the evil act.

* A condemnation calls on others to resist and not facilitate the evil act.

* Condemning someone makes you enemies, in a way that is plain for everyone to see. This positioning can open up for alliance offers from others with similar beliefs.

Making someone an enemy comes with risks and drawbacks of course. You become less able to influence someone if you cut ties, hence why people suggest to try influencing in private first.

John Paul II is widely credited with helping Poland overthrow communism. While he won't change the world overnight, there are millions of people even in Russia who respect the Roman Catholic pope, even if they aren't Roman Catholics themselves.

No but it puts the ball on their court