Scripture:

[1] The fool says in his heart, “There is no God.”
They are corrupt, they do abominable deeds;
there is none who does good.

Observation:

Notice that David is pointing something out about those who have closed their heart, not just their head, to believing in God.  These are people with very hardened hearts.
He goes on to point out that these non-believers with hardened hearts do abominable deeds and there is none who does good.  Perhaps one can do some good with an open heart and a mind not yet convinced of our wonderful God, but how can one do good with a confused mind and a heart hardened toward God.

Application:

This is not to say that all non-believers no nothing but bad.  Nor is it to say that believers will always do good.  But David is not just talking about non-believers who need “more evidence”, or “scientific proof”; those who do not accept as proof evidence of the finely tuned universe or many other logical arguments; he is talking about non-believers with very hardened hearts, not just weak minds, who lock God out of their lives.  It is saying though that without Jesus Christ as our compass we are easily led to evil due to our sin nature.

Some of us may be gifted apologists and be able to encourage and change the minds of those who’s minds are not accepting all the evidence for God around us.  That’s great. I wish I was as smart and quick as those gifted apologists.  Most of us though, should focus on changing hearts.  Work on those hardened hearts.  Show the love of Jesus with everyone we come in contact, and even more so to those we know in this condition.  We are called to sow the seeds and Jesus will do the rest.  If we continue to make ourselves available to Him Jesus will us for more than just the sowing, but it will be Him working through us.

Prayer:

Thank You Lord for replacing my heart with a new heart.  Thank You for the joy I get every day from knowing You are always with me.  Lord use me to help change the hearts of those who have hardened hearts toward You.  Put them in my path, help me to act as You will, and give me the words I need when I need them.  In Your Holy name I pray, amen.