Both of these questions should be answered on the basis of the biblical text as far as we have read so far.

Both of these questions should be answered on the basis of the biblical text as far as we have read so far.  I ask that you not do research.  But do not make things up.  Make sure you can prove anything you say with a biblical text, the more specific the better.  

Please make you answers brief:  1-2 sentences for no. 1, and a few for no. 2.

 1.  Abraham is the first biblical figure to believe (or, trust) in God (Gen 15:6).  The question is why.

In this regard, you may be misled by a comment in your HarperCollins Bible – that the description “means that he trusts God and his promise … It is … faith that takes God’s word as sufficient.”  Abraham’s response to God in v. 8, however, suggests the opposite. 

2.  In Gen 17, God makes a covenant with Abraham.  It is the second covenant in P and it is also commemorated by a “sign”:  circumcision.  Why is circumcision an appropriate sign of this covenant?