Can anything good come out of you?

How do we answer the question, "Why are some atheists/secularists good and why are some believers not?"

I know that the Bible says that there are none good, no not one. I am not questioning if mankind is sinful. Of course we all are. I am just grappling with trying to figure out where morality comes from. Experience shows that those who believe in God are not more likely to "better people," than those who do not believe. I know atheists who are much more concerned about the poor and oppressed and downtrodden than their believing counterparts. Why? Shouldn't followers of Christ have more sensitivity to the needs around them than someone who believes very little about Jesus, much less trusted him for forgiveness?

I think we have made too little of human potential. And before I am accused of converting to a secular humanist, let me explain. Even though I am not a secular humanist I do think we've missed how much potential we have for good. And I don't think this contradicts Scripture. (However, I may have to edit this post after the responses)

I want to start by saying that even the best of our human potential will never be good enough to satisfy the holiness of God. We will always fall short of giving God glory. I want this to be understood from the outset. Faith in Jesus is the only way to be brought to the Father in forgiveness. Now that that is clear, let me proceed.

Humans have the potential for great good. But we will never be as good as possible. Humans also have the potential for great evil. And we can be as evil as possible. Mother Theresa was a good person but she could have been even better. Jeffrey Dahmer was an evil person, and while it can be argued he could have probably been worse, I think it is fair to say he went out of his way to do evil things. We could cite more examples, but hopefully this shows what I'm trying to say. The doctrine of the fall of man does not teach that man is as evil as he could be, but it did leave him the potential to delve deep into evil without some sort of constraint. On the other hand what the doctrine of the fall of man does teach is that man is prevented from ever being as good as he possible could.

We can still be and act "good," (just not good enough). We were created in the image of God. God is good. Therefore, we were created for good. Creation was very good. When man ate the fruit of the tree it was not the tree of the knowledge of evil, but the tree of knowledge of good and evil. When that fruit got into the human system, they could still do good, but now they also knew evil as well as good. This is why humans, whether believers or not, do have a lot of potential for good. But in the end, they will always fall short of perfection in good.