Assumptions to Avoid?

As my bio mentions, I am majoring in the study of religion at the University of Toronto.  This is (Lord willing) my last year.  I am one course shy of completing my major in religion (though I am taking extra courses in biblical studies); the course I am missing is world religions.  Today in our course we were graced by the presence of a guest lecturer from another University.  His area of research is Old Testament/Septuagint studies.  Thus he delivered us an introductory lesson on the history of Ancient Israel followed with a quick lesson in biblical interpretation.

Methodology within biblical studies is one of my areas of interest.  A person's method can determine their conclusions.  Some questions that I find intriguing are: can a Christian committed to the bible adopt a historical-critical approach to it?  In what ways can a Christian apply modern scholarly methods to understanding the text?  In many ways, these methods elucidate and reveal much within the text.  But at other points, some of these methods can draw disastrous conclusions that could ship-wreck a person's faith.

Interesting enough, our instructor gave us four assumptions to avoid in order to interpret the text as a scholar:

1. The text is fundamentally cryptic - there are some texts that appear ambiguous and seem apparently morally wrong.  For example, in Genesis 22 how can God command Abraham to sacrifice his son?  Christians (or Jews) may respond to this by first claiming that though this may be the surface meaning, there is an underlying meaning.
2. The texts are a book of lessons ascribed to the reader in their day.  They must be modernized for modern use.  
3. The Bible does not contain any contradictions or mistakes.
4. The Bible is divinely given in which God speaks through prophets.

As mentioned above, these are assumptions that are to be avoided in order to interpret the text correctly.  Now, there are some scholars who claim that faith is compatible with being a biblical scholar.  But, the faith presuppositions must be dropped in order not to dilute/contaminate scholarly work.  If I may return back to my original questions, if a Christian is committed to the bible as the Word of God (as most evangelicals are), then it follows that once these scholarly methods are adopted, and these assumptions dropped, this basic commitment is essentially dropped. 

What hope is there for the Christian (I qualify this with evangelical Christian) within biblical scholarship?  I'll leave on one note:

This is why I speak to them in parables, because seeing they do not see, and hearing they do not hear, nor do they understand. (Matthew 13:13 ESV)