Let's look "logically" at the validity of the statement: "You can't take all of the Bible as truth."
--- That's all you can do.
What I mean is, with a piece of literature such as the Bible, it's either all true or all fake. There is no in between.
In the Bible there is no grey area. It's black or it's white-it's hot or it's cold.
With science, they can prove a thing by taking part fact and part conjecture or intuition and therefore you can say, "I believe this part but I think they're wrong with that part" and yet you can still have "faith" in the science institution. Why? Because you can pick and choose your truth and with the Bible the Truth is just sitting there. A mountain. Unmovable.
This is the Word of God not some theory. If you start saying that you believe this passage and not that one or that you believe this comandment but not the other--what are you really saying? Your not obeying the Word. You have no belief, and just like the people who worship science as the absolute in human achievment, you are making yourself your own god. Your deciding what you think is Truth and therefore going against the entire point of the Bible which is to learn how to worship and follow God.
Since the Bible claims (and remember I'm trying to be logical even though I know it is from God) to be from God and not from man, that is, physically written by man but through the Spirit of the Lord, any tampering with it's Truth by taking what ever you want and leaving the rest--is actually taking God out of it and therefore it becomes worthless.
You need it all. Every verse. Every word. Every truth.