How to produce a devil

The following is from Spurgeon's sermon,
"The Perseverance of the Saints" #872. Phil.1:6.

I have heard lately to my deep sorrow,
certain preachers speaking of conversions
as being developments of hidden graces
within the human soul. It is not so; that
theory is a lie from top to bottom.

There lies within the heart of man no
  grain or vestige of spiritual good.

Man is alien to all spiritual good.  He is
insensible and dead in sin. Spiritual life
must come to him from the Giver of life,
or he must remain dead for evermore.

If you could develop what is in the heart
of man, you would produce a devil,
for that is the spirit which works in the
children of disobedience.  Develop that
carnal mind which is enmity against God,
and cannot by any possibility be reconciled
to God, and the result is hell.