Joe tagged me with this (and the people I would tag have already been tagged, so I won't bother). Basically, anything good which gets raised too high becomes de-Christian; anything which is less than God which starts taking on divine attributes (especially perfection) becomes idolatrous and oppressive, and thereby de-Christian. So with that said...
1. Sola Scriptura: not just meaningless but, in so far as it eclipses the truth that a human being was the incarnate Word of God, anti-Christian.
2. Papal Infallibility: ultimately it is the consensus fidelium which is infallible, but even there, there are some things which we cannot stand just yet.
3. Private Judgement: source of the ten thousand things and all manner of distress. Has a role as part of an iterative process, it cannot be a final locus of authority on its own.
4. Penal Substitution: if suggested as one possible metaphor for understanding atonement, I can just about bear it; when imposed as the only possible understanding then it is the ultimate "doctrine of man" and graceless.
5. "Family Values": source of much of our present distress, and not something that Jesus was particularly supportive of. There is the individual in their relationship with God, and then there is the church family. Biological links come some way behind that, at least as Jesus taught.