[nobdysfool]

All Christian doctrine is contained in the Bible

Doctrine "x" is not contained in the Bible

Therefore, Doctrine "x" is not Christian.

And why is that a problem for you? That is PRECISELY what we believe! The logic is flawless!

Seems like the Catholic Church uses this one:

Doctrine "x" is not in the Bible

The Pope (who is infallible) says he believes Doctrine "x" is Christian

Therefore, Doctrine "x" is Christian

[RobbyS]

The logic is flawless, but your major premise is not in the Bible. It is an assumption that Martin Luther and other opponents of the Church found it necessary to propose after he had rejected what Catholics and the Eastern Churches believe: in the infallibility and impeccability of the Church.