We have the ability to do lots of things that God disapproves. Having the ability doesn't equal God's Will.
Look at the fact that a great deal of medical advancement came through Nazi experimentation on their "undesirable" populations... does that mean that all that comes out of it is evil? No... but neither does the good outcomes make the original act good. God can make all things new and all things (even when we try to do evil) accomplish His Will. That doesn't mean that everything we do, then, is sanctioned by God.
So why do you think God allowed the Nazis to do what they did? He knew they would do it prior to there even being Nazis.
Since God is infallible, doesn’t something He knows will happen, have to happen?