here is John Piper’s illustration of the difference between moral inability and legal inability and why a person can be held accountable for rejecting Christ even though they can’t choose Christ on their own accord.
Give it a listen and see what you think of the argument.
[youtube=http://www.youtube.com/watch?v=OzRdS_tdmAU&hl=en&fs=1&]
HT to Reformation Theology