I try not to question the motives of the evangelicals that I have known in the last 50 years.   They are a more diverse group than the political commentators make them out to be.   Kristoff points out some very good work by those who find the courage and energy through their faith, to do some very risky work with little personal reward.   

What I do resent is those who make abortion the only 'test' of faith that they seem to lean on.   Frankly, for some, the 'correct' view of abortion seems to them a moral 'get out of hell' card regardless of any other behavior that may afflict their lives.

Personally I'm on the side that believes we are all imperfect.  In relationship to a cosmic God who knows no bounds of space and time, there isn't much we can do to impress, or offend her.   The'ranking' of sin is not an expression of God's judgement, it's the expression of human judgement driven by human insecurity.