The best challenge, in my opinion, is the flip-flopping. Either they had it right once and changed to wrong then change to right, or they had it wrong and changed to right then changed to wrong again. Can't have both be right and wrong at the same time. Either the U.N. was bad or it wasn't. Why the Awake! articles praising the U.N. when they were members then giving up their NGO relationship once they were found out and exposed on the Guardian.
Hypocrisy will be the death of them, I feel. It's something that opened my eyes. The cross was a Christian symbol under Russell and then pagan under Rutherford, but the gospels point out, in the revised NWT, the "mark of the nails" on the hands, so more than one, and not at all as it's pictured on the magazines sinceĀ the sign saying the phrase about King of the Jews was above Jesus' head not his hands.
Either they can call God, Our Father, and they're children of God, or they are just friends, in which case they can't call God their Father. Who does the Bible say is "our mother", our spiritual mother is the Jerusalem above not the WTB&TS.
There's a lot of these reasoning points that make one think.