Why trust a cross?

In Don's middle talk of the UCCF Grad Conference (that between Psalm 1 and 2 Tim 4, noted below) he expounded Romans 3.21-26. He started by noting that the Trinity or resurrection are no longer the sticking points in student missions - rather, sin, wrath and exclusivity are the hard ones to get across. Yet those things are exactly the background and context for Romans 3.21-26. The first thing for 'getting' the solution is to 'get' the problem. A weak view of sin leads to a dissipated view of the cross (and vice versa). From here I hand over to Sean, who's helpfully posted his notes.